Matrix (S&T/AGM) MG42 - In-depth Look / Upgrade Blog
 

I will be updating this thread as I work on this project. My plan is to make this a support weapon capable of sustaining 26 rps with 7.4V battery. In hindsight, it might have been better to go with 11.1V with slower gearing for efficiency, but I already committed.

I am not responsible should you decide to follow my methods. It takes a certain level of skill and knowledge and it is advised to use care when working on airsoft guns.


The Gearbox

It took me a while to figure out how to remove the gearbox out of the receiver. It turns out the gearbox is a split-type. Once the associated bolts, brackets and QD spring are removed, only the tappet plate pressure keeps them together. Pulling the grip right of the picture allows you to clear the front lip and slide the two halves apart.

*If your QD spring guide doesn't want to come out, there is a trick that might work: Disconnect the battery and release spring tension by releasing the anti-reversal latch (ARL) via the access window hidden behind one of the piston grip. Once the ARL is released, the piston should return to near its resting position (if the spring was compressed to begin with). If you want, you can spin the sector gear a few degrees to clear the piston further (CCW in this picture), while holding back the ARL, if you think it's still partially meshed. You'll have to work against the force of the motor, so take care when doing this. If you are successful in rotating the teeth out of the way, you should be able pull apart the halves by overcoming the tappet plate spring force.

Alternately, you can just dry fire the gun a couple of times and go by feel to see if the piston has gone back to the resting position.

When re-installing the gearbox, make sure the piston is all the way forward and that the sector pickup teeth are spun out of the way.

If you're still having trouble removing the gearbox, this video demo might help:

<<Gearbox Removal>>


http://i1165.photobucket.com/albums/...2a9e08df1c.jpg

http://i1165.photobucket.com/albums/...3A239FF07F.jpg

http://i1165.photobucket.com/albums/...25BDA214C9.jpg

The top part of the gearbox uses T8 torx screws. This is a QD type spring guide similar to the M249, but on mine, it didn't actually come out after multiple attempts until I actually took the gearbox apart. I think the spring guide was getting caught inside of the gearbox.

It is worth noting that the spacing between the piston and the spring guide is about 1 cm shorter than standard gear boxes. Thanks for this info from Rafter_Man.

http://i1165.photobucket.com/albums/...8284EEA8DD.jpg

The QD spring didn't work for me because the spring guide was too big. With some 400 grit sand paper and a hand drill, I sanded it down enough for it to move freely even after the gearbox is tightened.

http://i1165.photobucket.com/albums/...BF9E280C64.jpg

The cylinder head is not a standard V2 one. The cylinder head nozzle is 21.3 mm long. The nozzle itself is also longer at 29 mm. It seems to have some sort of taper design and I could feel resistance as the nozzle is moved towards the cylinder head. I'm not sure what the purpose of this is because it seems to hinder tappet plate movement. There is some sort of padding, 2.7 mm deep, which feels a lot firmer than my 70 sorbo.

The stock piston head / cylinder combo has virtually zero compression. I can move the piston in and out of the cylinder with my finger sealing the cylinder head, with only slight resistance. Swapping in a new piston/piston head immediately improves compression.

Here are some measurements I took with a digital caliper:

Cylinder diameter: 23.85 mm
Approximate distance from the middle of the piston head o-ring to the end of the cylinder: 6.26 mm
Length taken up by Guarder cylinder head and 3/16" sorbo: 11.26 mm
Total cylinder length: 70.73 mm

With my setup, after the AOE correction, the cylinder to barrel volume ratio is about 1.21 with the stock 660 mm barrel. By shortening the stock barrel to 470 mm, I've lowered the ratio to about 1.7.

http://i1165.photobucket.com/albums/...52867996E3.jpg

From the top: V2, stock, V3 Marui Aug

http://i1165.photobucket.com/albums/...3C245ACBA7.jpg

I had to cut off the extra material on the cylinder head in order for it to fit. This will not be necessary if you can find a V2 cylinder head with extra long tip. At this point, I'm not sure if the extra long long even serves any function. I used a cylinder head with a long tip just to be on the safe side.

http://i1165.photobucket.com/albums/...0DFA4D0DCF.jpg

Note that the Guarder V3 Marui Aug cylinder head shows a bit of the first o-ring when installed into the gearbox. Compression was still 100% and it has another o-ring, so I didn't really think it mattered. No action was taken to correct this. I could have probably enlarged the window a bit to allow the cylinder to move up more to cover the o-ring and at the same time become compatible with standard cylinders, but I didn't think this is necessary at this point.

A problem I noticed with the stock cylinder is that it is not seated very straight. I noticed this when trying to improve efficiency and felt resistance at the end of the travel with the piston. I fixed it by removing material from the gearbox on one side and adding tape on the other.

http://i1165.photobucket.com/albums/...618_162823.jpg

http://i1165.photobucket.com/albums/...618_163918.jpg


AOE is at about 11:30 position.

According to this database, the PTS Masada nozzle might work? (Now, confirmed!)
http://forums.airsoftmechanics.com/i...p?topic=7734.0
http://forums.airsoftmechanics.com/i...?topic=10851.0

At this time, I wasn't able to find any PTS Masada o-ring nozzles, so I added an o-ring to this one made by Matrix. The seal improved, but still not 100%. I will probably change it to a proper o-ring nozzle later when I get a chance.

http://i1165.photobucket.com/albums/...26F6E62CFF.jpg

The tappet plate looks like a standard V2. When comparing with the SHS V2 tappet plate, the fin on the stock unit is more progressive.

One difference I did notice is that the spring post for the tappet plate is a few mm closer than your standard V2. This would explain why the stock spring is so much stronger. Testing with a stock V2 tappet spring doesn't seem to make a difference. I opt for the softer, V2 spring because it puts less load on the motor.

http://i1165.photobucket.com/albums/...615_111251.jpg

I did notice that the channel for the tappet is not very straight, especially at the front end. I had to sand it down flat so that there's less resistance when moving the tappet plate.

http://i1165.photobucket.com/albums/...9EF9864FB1.jpg

The lower gearbox is also held by T8 torx screws. There seems to be almost no grease on the bevel gear. No motor height adjustment mechanism can be found either. Luckily, the stock pinion position is pretty spot-on. When I put my JG blue in, I had to adjust the position of the pinion to get a proper bevel mesh. I also shortened the motor posts because they were a bit too close to the gearbox for my liking. When trying to shim the bevel to the pinion, I noticed that the cage doesn't keep the motor from moving. I wrapped aluminum tape from the motor to take up the slack. I later changed to a Lonex motor and that motor did not have issues with slack or motor posts.

http://i1165.photobucket.com/albums/...E18FF0F4DC.jpg

The gears all say "X" on them.

http://i1165.photobucket.com/albums/...F5F39C924B.jpg

Here is the trigger trolley. It's one unit with a return spring inside. The switch on top activates the motor on the drum. The switch seem to have been glued in place and is very fragile. Trying to pull it out with my pliers cracked the switch. I later pried it out with a pick instead. The button also feels very loose. Good thing I won't be needing it since I'm wiring it to the main battery. The contacts are close together so it's possible to pull the trigger slightly to shoot but not activate the feeder. Bending the contacts back should fix this problem on a stock unit.

http://i1165.photobucket.com/albums/...6F29FC3D40.jpg

The SC 10.44 SSG set seems to fit in the gearbox half, which should suggest that it will work with other V2 gear sets. (Note: The gears are not supposed to be installed this way, I just put them there to test axle spacing.)

http://i1165.photobucket.com/albums/...A6DA44AED0.jpg

A 3/16" sorbo pad seems to put this SHS piston and Guarder piston head at the right AoE.

http://i1165.photobucket.com/albums/...4103605ED3.jpg

The piston seems to sit pretty low. I had to shave off some of the reinforcement on the SHS pick-up tooth to allow clearance for the SC SSG 10.44 sector gear. I also had to remove the 2nd tooth and most of the 3rd tooth.

(I used the spring when testing the actual AoE job.)

http://i1165.photobucket.com/albums/...91ECBF55C8.jpg

SC SSG 10.44 gears fitted in the gearbox. The ARL is not shown in this picture. Notice that handy little window that allows you to release the ARL without taking the GB apart.
Note: The safety is a combination of a trigger block and spur gear block. I think the actual safety button used to slide over the spur gear's teeth to prevent it from spinning. Since, my SC gear set has a smaller spur gear, this part of the safety is no longer there.

http://i1165.photobucket.com/albums/...BAA90066DC.jpg

Notice the aluminium tape I used at the top and around the motor to reduce play. This made satisfactory shimming possible.

http://i1165.photobucket.com/albums/...06B93C177C.jpg



The Barrel GroupThis section is under review. Modify at your own risk.

This is the metal hop up chamber. It has a sliding mechanism that adjusts hop. Does anyone recognize this from another gun? I would like to know a backup source in case this breaks.
The barrel is about 660 mm long. Looks like a standard AEG barrel. There's a groove cut about an inch away from the muzzle. I'm not sure what it's for, but I'm not particularly interested in making this gun accurate (volume of fire over precision), so I didn't bother with the details. It seems like a good place for a stabilizer o-ring.
I also noticed that there was no barrel stabilizer ring at the chamber. I'm not sure if I've lost it, but I slipped on one that came with my Lonex bucking, and it didn't really want to stay. It was too loose on the barrel such that it is free to slide out on its own, so really it does nothing to stabilize the barrel.

Inner diameter measured at near the muzzle is approximately 6.15 mm. It's difficult to measure bore diameter with the caliper, this is the best measurement I took.

Later I discovered that the ring was likely left out on purpose. More on this later.

http://i1165.photobucket.com/albums/...B6FD792C35.jpg

http://i1165.photobucket.com/albums/...DC0DDC3DDE.jpg

The I cracked the holding clip for the barrel while trying to remove it. I'm not sure if this is the part's fault -- I'm never good at removing these... The bucking also ripped while I was trying to remove it.

http://i1165.photobucket.com/albums/...8E6724CF4E.jpg

Trying to install the upgraded gearbox in the gun along with the hop-up, I ran into a problem. It seems the stock design has a lot of give around the nozzle, but when I changed it from the stock, plastic, stepped nozzle to a straight, metal nozzle, it interferes with the chamber in such a way that it's difficult to cycle the tappet. I highly recommend that you check for this interference before shooting. You can do so by cycling the tappet plate with the barrel group installed.

I looked into this problem and this is what I've found: The chamber is aligned to the gearbox via a square cut-out on the front of the gearbox. In theory, this is great, as the chamber is perfectly squared to the gearbox. The problem is, the outer barrel and gearbox alignment is not good. When you try to force the install, the result is that the loading end of the inner barrel will push down on the chamber, putting pressure on it and deflecting it slightly in the nozzle 's way, causing it to hit the top part of the chamber. I believe the brass barrel ring was left out for this reason, to allow the inner barrel to have some range of movement. With the brass ring in, the install became even more difficult.

To fix this problem, you can:

1. Raise/angle the outer barrel up slightly to relieve pressure on the chamber. You can do so by modifying around this brown plastic piece, which secures the back end of the outer barrel.

http://i1165.photobucket.com/albums/...E36B00C677.jpg

2. Adjust gearbox alignment by slotting the screw holes for the gearbox halves. I didn't do this because the weight of the whole gun will be loaded on the gearbox and I didn't want any chance of movement created by the slotting. Someone with metal working skills may be able to do this successfully. As a matter of fact, the stock receiver seems to be slightly slotted already, possibly done at the factory in an attempt to allow the tappet/nozzle to cycle.

3. What I did to fix this problem was shimming the bottom of the chamber to force alignment of the nozzle with the chamber. The inner barrel will try to force the chamber to bend downwards, but the shimming will force the chamber to stay in proper alignment with the nozzle. In my case, I happened to have some unused PCB board lying around, which I glued onto the chamber, but in theory you could use any rigid material.

http://i1165.photobucket.com/albums/...3B7D1DB851.jpg

http://i1165.photobucket.com/albums/...E477897CBD.jpg

*Note: Allowing the inner barrel to be at a different angle to the chamber may* cause feeding issues or air leaks depending on the extend of the modifications and bucking type. Be sure to fully test your modification, for whichever one you choose. As said before, accuracy is not my top priority, so the fact that the gun fed was good enough for me.

**Note: There is a screw that attaches the chamber to the gearbox. DO NOT over-tighten this screw as it will also cause interference with the nozzle.

***Note: Whichever method you choose, check the loading dock/platform as it sits directly on top of the hop chamber.

Thanks to duggan69, I've been informed that the later version of this AEG comes with a spring that pushes the chamber against the gearbox. I investigated and noticed how this may be beneficial. The horizontal screw acts as a locator to line the two pieces up, but it doesn't do a very good job since it doesn't prevent rotation in all planes. Over-tightening it causes mis-alignment issues, so that's not a good solution. Having the spring there helps to insure that the nozzle and bucking are at a consistent distance apart. I cut a small section of an sniper spring and installed it around the inner barrel, in front of the hop up.

Screw loosened to demonstrate point.

http://i1165.photobucket.com/albums/...616_210551.jpg

http://i1165.photobucket.com/albums/...616_201527.jpg


The Drum

Drum motor upgraded with Virtuabotix N20 Micro:
http://youtu.be/tju5xhqdtq4

I'm quite happy with the way it turned out. By my calculations, it is now feeding at about 24+ bps with 4 AA batteries, as supposed to the ~15 bps from the stock one. The bb's in this video were KSC 0.30 g's. In this experiment, I was using the stock battery holder containing 4 AA batteries. I measured the voltage to be about 6.36 V, using a multimeter. The current of the new motor was ranging from 0.10 A to 0.15 A.

Motor:
https://www.virtuabotix.com/product/...3-7v-25000rpm/

http://i1165.photobucket.com/albums/...86128903_n.jpg

Inside of the drum's gearbox.

http://i1165.photobucket.com/albums/...B8E8BE2387.jpg

I've added a mom-on switch to the drum so I can "prime" the feed tube without dry-firing. It is a SPDT switch. Why SPDT? I used it isolate the gun's circuitry so that pressing the priming switch won't cause the gun to cycle. I'm sure there are simpler and more elegant ways of achieving this but my knowledge is limited in the subject. I also bought this switch by accident, which worked out pretty well in the end.

Here's a simple schematic of the wiring design I used. The push button switch is normally connected the gun's circuit, but when you push the button, it disconnects from the gun's circuit to prevent the running of the gun motor.

http://i1165.photobucket.com/albums/...SPDTWiring.png

http://i1165.photobucket.com/albums/...5AE8ADC63A.jpg

http://i1165.photobucket.com/albums/...A4A2230349.jpg

Note that when using my design, touching certain connectors will cause the gun to fire. That is why I "gendered" the connectors and place the connectors in the following manner(put distance between the two male connectors on the gun's side and insulate the female.). Care should always be taken whenever the main battery is connected. The connectors I used are 2.0 mm bullet connectors.

http://i1165.photobucket.com/albums/...E7515C82CC.jpg

Since, the drum runs whenever I pull the trigger, I wanted to synchronize the feed rate of the drum with the rof of the gun as much as I can. I believe doing so gives the best efficiency*. Slow feed rate limits rof, and the gearbox would be cycling more than necessary, adding wear. If the feed rate is too high, the gun will not be able to keep up and it will only shoot at the maximum cyclic rate of the gearbox. This will also add unnecessary stress on the drum's motor since the gun will not remove bb's faster than the drum push bb's into the nozzle, causing a momentary stall before the nozzle moves out of the way and allows the next bb to chamber.

*I realize the gun's gearbox works in cycles and it doesn't remove bb's from the chamber at a constant rate (but rather like a pulse). I still stand by my theory that matching the rates yields a good balance of stress vs. performance.

I used a series of 10W resistors adding to 6.5 Ohms (specified), which resulted at exactly the target of 26 bps.

Here are the results of the various combinations of resistors that I tested with:
7 Ohms = 25 bps
6.5 Ohms = 26 bps
6 Ohms = 27.7 bps
3.5 Ohms = 28.7 bps

I plotted the four data points on a graph but it didn't really produce anything concrete. I got to my target before I needed to use that much data. The plot almost resembles a logarithmic function. With the resistors in series, the current draw went up to around 0.19 A.

***
Why not a voltage regulator? A voltage regulator is a great idea since it supplies the feed motor for the exact voltage that it needs for a certain speed but after doing some research on ASM, I believe that it is better to use resistors since the voltage of the main battery will drop along with rate of fire as it is being used. It is believed that both the rate of fire of the gun and feed rate will drop similarly together.

If you want to use a voltage regulator, here are some part numbers as suggested by philsaudio on ASM:

***

To help speed up the testing process. I used an old brass barrel, plugged one end and counted how many bb's could fit in it. In my case, that's 74. I ran the drum for a given amount of time, feeding the bb's into an empty box. At the end, I counted how many times I could fill this barrel, plus whatever's left.

For example. IF:

Ran the drum for 9.56 seconds
Filled the barrel 3 times
Still had 15 bb's left in the box

74 x 3 + 15 = 237 bb's
237 / 9.56 = 24.5 bps

The drum was feeding at an average of 24.5 bb's per second. Beats counting bb's 237 times. ;) This method is confirmed by chrono testing with the gun.

Hint* If you just short of a full barrel, you could always count how many more it takes to fill the barrel and subtract. Example:

My barrel is not full. Adding 15 more bb's makes it full --> 74 - 15 = 59 bb's in the barrel.

http://i1165.photobucket.com/albums/...5C47662310.jpg




Others

This is the feed adapter block. I got an extra long screw, washer, and nut to secure this empty belt. I used a 6-32 thread screw, which seemed a bit loose but I wasn't able to find anything else that fits, as 8-32 was too big. The nut seems to do the job of holding things down.

NOTE* Someone kindly pointed out that I had the links on backwards! They are installed incorrectly in the pictures below. I will update the pictures when I get a chance to fix this.

http://i1165.photobucket.com/albums/...28F2527966.jpg

http://i1165.photobucket.com/albums/...7D41196501.jpg

Sling - The sling attaches to the piston grip at one end. Make sure you get the late production model, meant for MG42. The early production ones are too narrow to fit on the grip.


Additional Notes

Reserved for future updates.

Interested to hear more!

I'm currently working on getting the motor in the drum mag upgraded. Once I sort out the details, I'll update here and add pictures.

KenTsui, thank you for making this thread. I just recently got my MG42 and so far the information you have provided has been immensely helpful to me. I had to create an account here just to thank you and you ask you some questions that I hope you would be willing to answer and help me out with as other concerns I have come up.

First of all, To remove the gearbox I see that you need to remove some screws from the outside of the body, from the looks it appears to be 4 (two on each side) there along the top of the receiver. I take it these screws are Metric sized as my Imperial allen keys do not appear to fit well enough to turn the screw without fear of stripping it? If so I need to get me a set of metric keys then.

I ran into the same issue with the box mag that you did where I could pull the trigger and only fire the gun and not the box mag. With a little extra "squeeze" on the trigger the box mag engages and everything works fine. I saw that you mentioned that you wired your box mag to the main battery...are you running your magazine off of the main battery power as well or just so that it ensures both the gun and the box mag activate when you pull the trigger? Can you explain where and how you wired it to achieve this?

Lastly, one issue I have encountered...When firing my gun, sometimes the springy feed-tube for the BB's that you insert into the plastic hopper box actually retracts and comes out of the plastic hopper box because, from what I can tell, the force of BB's being loaded into the spring create a back up and that pressure makes the spring tube back up and pop out of the hopper unit. Have you had this happen to you and if so what did you do to resolve this? Or is there something I am doing wrong here? Right now I am simply using a few small strips of duct tape to hold it in place and it appears to work fine with that.

Other than those questions I highlighted in pretty blue, I might have some more come up in the future as I look to upgrade my own MG42... I hope that you would be willing to provide help should I need it.

Thank you for any and all help that you provide!

Thanks,

Rob H. from Houston, Texas.

Hi Rob, you are welcome! I'm glad I can give back to the community.

You are right, the allen screws seems to be metric. I did manage to get a few loose with imperial keys, but I feel like I was stripping them, so I switched to metric and it fits much better.

I did wire the box mag to the main gun battery. I did so by:
- wiring a positive wire to battery positive (I suppose you could splice anywhere on the positive wire.)
- wiring another wire to the drain tab of the mosfet (I suppose you could also splice off the motor negative wire or even from the motor negative terminal, but that would be just giving yourself more work. It was easier for me to run another thin wire from the mosfet.)

*If you are not installing a mosfet, I would just run wires parallel to the motor wires:
- positive wire to battery positive or positive motor terminal
- negative wire to motor negative terminal (or trigger contacts, but again you're just make more work for yourself trying to fit all those wires)

**Warning: The voltage for your main battery is probably too high for the feed motor, you'll need to make the necessary calculations and step down the voltage with resistors in series to the feed motor. Let me know if you need help with this.

***Important: Make sure you check the direction of the feeding wheel after the wiring. Make sure it spins the right way before trying it out to prevent damaging the gears!

This way, the feed motor gets power every time you pull the trigger. Your gun runs, the feed motor runs. The motor I used takes very little current (0.15A) so it doesn't really slow down the gun's ROF. One thing I haven't done is wire another pressure switch for "priming" the bb's in the feed tube. To do this now, I have to dry fire until I see bb's come out of the barrel. I guess this is not a big deal, unless you want to be stealthy and setup for an ambush.

I haven't actually run into the problem of the feed spring/tube falling out of the plastic port block. Maybe look inside the drum and make sure the tube is fulling extended and make sure there are no unnecessary bends inside of the drum?

If that fails, I think they are pretty easy to come by. I haven't confirmed this but the item on this link is supposed to work as feed tube for the M249.

These part numbers are part of a larger list from ASR.

Just put the part numbers in http://www.mcmaster.com/ and you should see them.

This is my first MG and it was quite a learning experience for me too. I'm glad to meet another fellow MG42 owner, because I wasn't able to find much info out there when I first received the gun. So, feel free to ask any questions and I'll do my best to answer them. I might ask for your help in the future if I get stuck somewhere. :)

KenTsui - Thanks for the quick response! Very helpful.

Yeah I had a feeling the screws were metric when I wasn't getting much if any grip and the next size up was too big. As far as wiring the magazine to the battery...I might do that some time down the road..but as of now it works fine so I don't necessarily see much of a reason to do it right now eh?

Since I haven't been in the gearbox nor do I plan on it until something breaks...how would you gauge the quality of the gearbox shell and internals? Pretty beefy or did they go for cheap on it and cut corners? Seems pretty solid from what pictures you have taken. I am not unfamiliar with gearboxes at all so when the time comes to do repairs or maintenance it shouldn't be much of a hassle for me I don't think.

Lastly...as this one took me by surprise. Evike.com's website shows that this gun shoots about 350 FPS...mine chrono'ed at 420. Any idea why there would be such a discrepancy? Did Evike not chrono their test gun and just take what the manufacturer said it was shooting at? I am curious now to want to open up the gearbox and see how good the compression is on my particular MG42...maybe it was better than yours (you said you had poor compression on the piston)

I also have that HUUUGE annoying orange flash hider at the end of mine. I plan on just getting some Automotive engine primer and laying down a few coats inside and out with it, taping off areas I don't want painted and making sure when i paint the inside of it that it doesn't get paint in the inner barrel (prolly stuff a cotton ball in there or something). After the Black Primer I'll lay down a few coats of matte varnish to give it a shell of protection so it doesn't chip or scrape off as it comes into contact with the environment during play.

It's definitely not necessary to wire the drum to the gun battery, I just did it for sake of convenience. I always forget to charge my AA's. Plus, I needed the extra voltage to keep up with the rof.

The gearbox feels pretty beefy to me. I'm not an expert when it comes to MG's, since this is my first one, but I don't really see any weak spots in terms of strength. It's definitely more reinforced than your standard V2. The weight of the gearboxes gives me the impression that it's not overly cheap. The lower GB is pretty spot on with axle spacing and construction; although, I'm not thrilled about the way it mounts to the motor. The upper on the other hand, seems to lack precision: Tappet channel is not straight, spring guide hole is too small, cylinder window short (not sure if this was purposely done), cylinder head posts with relationship to the cylinder window doesn't seem quite right (showing some of the o-ring on the CH). They mate together pretty well though, I'm glad about that.

I'm not sure what it chrono'ed at but I gave Evike special instructions to install an MS120 spring to make it over 366. I haven't tested it after the nozzle upgrade but I think it was actually shooting around 1.25J with the spring they gave me. There was a spare spring, presumably stock spring, inside the box, but no sign of the empty Prometheus spring box... For all we know, maybe the stock spring was already M120. I used their customization service and specified the spring (saved $5). It pisses me off that they have to charge me 1 hour of customization work to swap a QD spring!
Edit: I just remember you are from Texas. In case you didn't know, it is required that the airsoft gun shoot over 366 fps with .20 in order for it to import into Canada.

I did exactly what you described with the flash hider, but I advise you to sand the tip before priming, as it took several attempts to actually apply the Krylon primer that I used. For some reason, it didn't seem to want to stick (I got lazy and skipped the sanding). I also did a pretty crappy job of masking and ended up getting some over-spray over the hand guard. Once the matte black paint dried, you could clearly see how the factory paint is actually a bit glossy.

Oh yeah, forgot to mention that to you...you should sand it down and wipe it down with warm water and dish soap to remove any of the plastic release agent from the mold. Sanding it gives the Primer a surface to stick to. I recommend finding the automotive primer as it is made to be thick and durable and then of course sealing it with the matte varnish to just give it a hard shell clear coat to protect the primer from chipping and scratches.

Agm mg42
 

Hi KenTsui congrats for this post. I took a look at the pics and read the whole review. Two weeks ago I bought from Germany a GSG (AGM) MG42 with 0,5 joule. I finally succeeded to replace the spring and I put a M120 spring. In future I intend to replace the head cylinder and the piston but I don't know how to take out the gearbox from the body. Do you have any advice? Thanks!

Hi, I can't comment on the AGM MG42, but for this S&T one:

You remove the c-clip and the pin behind the pistol grip and you should be able to move the whole lower gearbox backward and down/out. Tappet plate tension keeps it from falling. Removing the main spring helps to remove tension on the gears as well too. It takes a little bit of strength.

If you look at my first pic, you'll notice the two lips, one at the front, and one at the back. These lips keep the halves together when it's in the forward position.

Great review, love all the minute details you included. For the hopup, ak's use a sliding arm that goes up and down, so maybe a modified ak hopup could work.

That's true. The AK hop up seems to resemble this one but I've noticed that the one on the MG has a box termination. It was designed to fit squarely at the front of the gear box for alignment purposes.

I wonder if something like this will work because it looks like there is an alignment hole at the back like the one in the MG.

http://www.evike.com/products/36726/

I'll be referring my GunTech to this page once my MG42 is in. Lots of good information here

Hello,

I just registered to say a few things;
First I should thank you for this thread, it is the only review I could find on this MG(I own this one myself obviously). I had to change the spring, but since the center guide is stuck in the upper part of the gearbox I had to open it. I got stuck at one point and was only able to continue when I found this thread and learnt about the little spring which you mentioned in the pistolgrip.

Secondly, the one I have is the AGM MG42, which is actually the same gun from the same factory as the S&T/Matrix MG42, just with a different brand on the box. I actually wanted to buy the gun from Evike, but then they decided not to ship abroad.
Unaltered the gun shoots 420fps, too much for fields around here(Belgium).

Also, be careful with the externals, they are rather fragile. The feedingtray on mine arrived with damaged hooks and had to be replaced(now an expensive hardened steel feeding tray with a ten year warantee on it). The aluminium in which the gun is made is flimsy and bends quickly.
I havent been able to take it to a game myself but have already heard from other users about a number of smaller problems with this gun, like batteries in the drummag loosening and the mag no longer feeding when firing on the move because of it.

I hope you dont mind digging here for this purpose.

Thanks for adding extra information. I'll add this quote to the bottom of my review for others to see if you don't mind. :) I will also update my title as I remember the AGM thing in the WW2 thread, according to a trusted source.

I also had a problem with the feeding tray hooks. They were too far apart and did not allow a solid mounting of the drum. I took a risk and bent them closer together. Thankfully, it did not break off, but you are right, all the metal parts feel weak.

Thanks for the review. As a WW2 weapon fan, this mg42 looks pretty nice to me. :)

Thanks for this blog, I am having real issues trying to remove the spring, the thing just seems jammed but I will try and use some of the tips to get it out.

The hop also seems to have no effect what so ever so I was hoping to try and access it. I assume you have to remove the gear box so you have to get to it by removing the trigger and grip as well as the side screws on the reciever?

Thanks again!

Yea, it seems like everyone is having problems with the QD spring. Just do your best to spin the sector gear so that it's not engaging the piston and release the ARL so there's as little spring/piston/sector interaction as possible.

To remove the gearbox, yes, you have to lower and the screws on the side of the upper. If you don't split them apart, you can't take them out of the receiver.

To access the hop-up chamber, technically, you don't have to remove the gearbox. That's provided you are comfortable with taking the barrel retaining "C" clip off while it's still in the receiver. After that, just slide the inner barrel forward and there'll be only one screw that holds the chamber to the gearbox.

It's probably easier to just take out the gearbox though. You'll have to eventually fix the QD spring anyway if you ever plan on having this feature. Also, it will make taking out the gearbox a lot easier in the future.

Thanks for the quick reply, I have to admit though I still cant get the gearbox out! I managed to get the grip to slide a little back and forth but the whole thing is still jammed!:banghead:

Any chance you could post a pick highlighting which actual screws to take out and in what order? A lot to ask I know but this is really stumping me.

Regards

Okay, I will try and do something like that when I have time tomorrow.

Cheers mate, I would love to get this sorted out for this Sunday...

As promised, this might help those of you having trouble with removing the gearbox. It's my first instructional video, so go easy on me. ;)

http://youtu.be/SyTptjSsyRo

KenTsui, I thank you!

Spring changed to a more face friendly 330fps and hop unit fixed!

Thanks again, that youtube movie was invaluable!

Let me fix your mg42......
 

Having problems with your mg42 gear box and drum mag. Don't have the inclination to fix it yourself. having fielded this in orig configuration and having it fail miserably....I decided to fix that once and for all. I can help you too.

Let me rework and rewire it for you. When the gear box is repaired you will get better performance from the drum mag with out the constant feeding problems. you will no longer need to use the drum battery pack.

All you need do is send me the gearbox and top and bottom. I will fix, then send back. I can do any upgrades to it. if you want you can send the drum mag also. All my work is double tested.

email panzerjj@hotmail.com or shoot me text here

Hey kenTsui!

Wanted to follow up,with you on my AGM (S&T which is the hub that distributes for AGM) MG42.

Worked with a pretty skilled tech who used to work for G&G who happens to be super OCD about making guns work perfectly. Anyways, I left it with him and here's the initial tweaks and upgrades he did.

Shimmed the gears - he says the gears are pretty solid for being Chinese...recommends running them until they give out

Shimmed the hop up slider so that it doesn't jerk around when trying to slide it..it glides much better and will hold the setting without vibrations moving it

Replaced piston and cylinder head, these he said weren't great and already showing wear even after 5k rounds cycling through it.

Greasing the gearbox (always a good thing)

Soldering the wires to the motor

Installing a mosfet on the trigger.

And for me, most importantly is rewiring the trigger so every time the gearbox fires, the box mag motor winds. Which, as the tech was telling me, was pretty stupid how they wired the trigger. The trigger contacts are copper, but the box mag is actually a pressure button that the trigger when pulled (with good force) pushes the button to make contact to wind the magazine. He says this was completely pointless, costs more money to manufacture, and isn't as effective as just wiring it with the trigger contact!

So anyways, needless to say, he wired the trigger to make it how it SHOULD have been (but better cause he's OCD and gave it much Love and Care)

I get the gun back Saturday and going to a game on Sunday. Can't wait to see how she does!!

Thanks for your input, I've pretty much done everything you listed. It's good to have reassurance from a good tech. http://www.airsoftcanada.com/images/...01_icon_ok.gif

Although, I'm not quite sure what he meant by shimming the slider on the hop-up. I tightened the screw on mine so it won't lose its setting but loose enough so that it can still be adjusted.

He said he put a shim between the hop up and the screw or something. Basically, he disliked how when you tried to move the hop up it would jerk from spot to spot, so he gave it a little buffer to make it glide better and be less likely to lose its setting from vibrations and such in the gun

Hi KenTsui, your upgrade blog is excelent, thank you so much.

You should know that the 650mm barrel is definitly to long for the cylinder in this gun. Even a bore up kit probably won't be enough. I upgraded mine to a 6.03mm 509mm Madbull V2 barrel. Also, after chronoing mine i noticed that the FPS values didn't seem to match what the spring should deliver. The reason for that isn't an airseal issue though, but due to less compression on the spring. The R&D department who thought up that Gearbox left about 1cm more space between the cylinder and the base of the springguide, resulting in less compression and so less energy output.

Also I tried various nozzle/bucking combos to achieve a good and constant airseal. I installed two aftermarket airseal nozzles, the one you used(i also added an O-ring), which gave me horrible FPS differences (maybe do to the HU/GB missalignment) and a czech made one which worked better but was still off. But both nozzles don't have that tapped design the orginal MG42 nozzle has. I achieved the best results with the original bucking/nozzel combo after i added an O-ring to the nozzle. And I also removed the screw between the hopUp chamber and the gearbox because in my gun somehow, it was the reason for the mentioned misalignment between the HopUp and the GB. The spring pushing the HU to the gearbox is more than capable to hold the hopup in place.

Good points! It's funny you mentioned that, because this week I actually cut down the inner barrel.

I'm now using a 470 mm inner barrel, which, by my calculations, should give me a ratio of about 1.7.

I noticed the nozzle design difference when switching nozzles. So I measured the position of the bb with respect to the OEM one. I ended up using the Core PTS Masada nozzle. Some shaving of the tappet plate may be required to get that extra half a mm.

I hadn't noticed that about the spring compression length. Now I don't feel so bad that I'm not getting as much fps as I should. Thanks. :) If you don't mind, I'm going to add that to my first post.

509mm barrel eh? Looks like I know my next upgrade. My tech guy even said that the stock barrel was junk and too long but didnt have "long" inner barrel in stock at the shop. Of course we happen to be talking about the issue with the barrel practically the same day you guys mention it as well. I think dropping it down to the Madbull 6.03mm x 509mm long barrel would be beneficial...especially since the stock one is junk.

I did get to play with my gun yesterday after all the other work had been done on it...my tech went as far as to fill in the underside of the plastic BB loading tub that the Box Mag feeding spring inserts into with hotglue to add some weight and he leveled it out on the bottom and added velcro to the underside of it as well as the metal tray that it sits on top of in the body of the gun... If you remember KenTsui i mentioned how the spring would pop out and i was having the use some duct tape to hold the feeding tube spring in place? Yeah...not anymore!

The shimming on the hopup worked real well, infact, he also took out the big spring that applied pressure on the hop up as that wasnt necessary after he worked on it.

I used my MG42 at a game yesterday for the first time since all the work...No problems with it firing, no problems with the box mag feeding or loading, trigger works great winding and firing the gun...overall just great performance thus far. Next step is installing a new barrel and probably adding some electrical tape around the barrel at various parts to keep vibration down and support the barrel with the help of the outer barrel.

Oh, lastly, KenTsui:

Do you have a link of the correct MG42 sling I need to purchase? You say to get a late production sling...if you can point me in the right direction that would be so great of you!

This is where I bought it. It's not necessary the best place to do it, but after wasting money on the incorrect one, I took a gamble here, and it paid off.

http://www.epicmilitaria.com/product...-leather-sling

The late production of the MG42 slings fit both the MG34 and MG42, but the early production models only fit the MG34. So just because it fits the MG34, doesn't mean it fits the MG42.

It's difficult to tell whether it'll fit or not from online pictures. The first one I bought said "MG42/34" sling but it was in fact, the narrower version.

I took the time to take some pictures of the mods I did to the boxmag. I rewired it just like you did KenTsui, because, lets face it, priming the mag is awsome ^^ who wants to dry fire that beast? No one.
And because i hate rattling I also cut up a pc noise absorber matt and lined the inside of the boxmag with it. Works pretty well and it is alot quieter than before. Also You inspired me to cut up some dummy rounds and put them over the feeding tube. I dusted them metallic black to look more like german WW2 steal casings which where painted black.

http://abload.de/thumb/imag01901qujj4.jpg

http://abload.de/thumb/imag02031o4knn.jpg

http://abload.de/thumb/imag02041wmjen.jpg

Also Kentsui check you ammo links on the feeding tray insert. It looks like you put them on upside down.

Hey, great idea with the lining. I hate the rattling too, although it should in theory reduce the ammo capacity. What's another 100 rounds when you got 2000+ rounds, right? :lol:

OMG, obviously I haven't done enough research. Thanks for the correction on the direction of the link.

MG42 feed tray
 

Have you (or anyone else) had any luck in removing the feed tray of your MG? I'm converting mine into a MG3, and I need to remove it to install a RS MG3 feed tray (so I can mount the box magazine). Also, from the looks of it, the motor is a short-type? Would you say it would last a while, or should I go about replacing it with a nicer high-torque motor? Thanks for your time, and beautiful build!

Though I haven't tried, I've been told that the tray and top cover is held by a pin. A tap with the hammer should get it out. Carefully study the pin before you do so. If memory serves, you might need to rotate it so that it clears.

Yes, it is indeed a short-type motor. I never really studied it that closely but I would think it's consistent with most stock AGM AEG motors.

If you are not doing any kind of crazy build, there's no reason you can't keep using the stock one.

I was asking about the motor since I've noticed that mine heats up considerably from sustained fire (out of the box my gun is shooting 450 FPS). More so when I use a 9.6v Nimh over my 7.4 Lipos, I get a ROF boost but my motor heats up quite a bit more.

Woah. Mine was shooting way less than 450 fps in stock form. If someone upgraded it with a stronger spring, that could add load to the motor and if the stock motor is not strong enough for that spring, it could add heat. I'd stick with the lipo since they generally have higher discharge rate, avoiding chances of starving the motor.

I personally haven't used the stock motor that much, so I can't really be of help with the specifics.

In my report, I mentioned several of things I did to improve efficiency in the gearbox. I noticed these things partly because I measured the efficiency of the gun using a watt-meter and it wasn't where I had expected. Every little thing added up to a couple of rounds per second improvement, a drop of couple amps, and conceivably, less load on the motor.

What do you mean by starving the motor? And wouldn't a higher discharge rate mean a higher ROF? Or am I getting things confused?

Sorry for confusing you. Maybe I shouldn't have added that part since it has little to do with motor heat.

What I meant was that lipo's generally have a higher discharge rate (unless you're using a really bad one), meaning it will more likely supply enough amperage to keep up with the motor.

Higher discharge rate doesn't necessarily mean higher ROF unless the other battery you are comparing the lipo with doesn't have enough juice to keep up with the motor's demands.


For example:

Suppose battery #1 can output 10 amps and your motor needs 15 amps. Your motor is "starving" because it doesn't get the 15 amps that it needs. The result is reduced rof.

Swap it for battery #2, which can output 20 amps, then your motor is happy and you will see a higher rof.

Had battery #1 been able to output 15 amps or more, then you wouldn't see any difference when you put in battery #2.

So maybe the amperage of my Lipos isn't enough, since there is a very noticeable difference in gun performance when I switch batteries?

The only way to know for sure is to measure the amp draw of the gun.

Replacement trigger contacts
 

I've recently aquired everything I need to SMP my MG42, but I have to resolder my trigger contacts for the installation. Do you have any idea where I could get a spare set, if I decide to go back to the original AEG design?

Sorry, I'm not familiar with the SMP. How do you manage to fit the trigger board into the MG42's gearbox? If it's simple re-soldering, couldn't you reuse it?

Any diagrams for running the box mag off the power of the gun? I was thinking of soldering the activation wires to the trigger contacts. Bad idea?

You only want to do that if you are running the box off the gun's main battery. You do that by running the box mag motor parallel to the gun's motor. That way, when the gun's motor runs, the box mag motor also run. The problem is the voltage supplied to the box mag will be same as the gun's, which could be too high.

This is essentially the same as what I've done, but I have a mosfet in there. You may experiment with resistors to slow the box mag down. I've bought some voltage regulators that I haven't played with yet. I'll report back when I do.

Having that said, I've heard from people running the box mag with the main battery at 7.4V and they haven't failed yet. I suppose you could do that until the box motor goes. They are pretty cheap to replace anyways.

if i was considering buying an LMG and i was considering either the PKM or MG42, would you recommend the MG42?

It's hard to make a comparison when I don't own a PKM.

I've commented on the quality of this MG42 in the first post in a few places, it's by no means perfect, but if it is acceptable to you for the money, then go for it! :cool:

I'd say both replicas are pretty unique, perhaps the MG42 slight more so.

well for me it comes down to being able to use it with a Vietcong Loadout, because we always lack LMG's.I haven't read anything that makes me thing A&K's are very reliable.

Having read the blog on your MG42 mods has encouraged me to go out and get one. So, I just picked mine up today. I was just wondering what kind of 7.4V lipo are you running in there. Something like a 7.4V 2000mah 15C perhaps? I am still in the process of learning about lipos.
Any input is appreciated.

I actually changed my previous plans and changed to a 11.1V lipo. I find that with the rate of fire that I wanted, it was more efficient to run a 11.1V.

I'm afraid I won't be much help here because I am running the battery outside of the gun, inside of a battery pouch, so I'm not restricted by the size.

If you're running 7.4V, that battery spec you posted should be fine for stock.

Voltage (7.4V vs 11.1V) - This depends on your rate of fire. If you plan to upgrade the rate of fire, the drum, and internals like I did, then I would suggest 11.1V. A 7.4V is good enough for a stock gun with normal rate of fire. Actually, most support players would might prefer a more moderate rate of fire to conserve ammo.

mAh rating - The larger this value is, the longer you can stay on the trigger and on the field. This is important as a support player, since your task is to suppress and provide sustained fire. You don't want to run your lipo completely dry. This is dangerous and bad for the lipo's life. With a 2000 mAh, I estimate you should be able to run it for about 5000 rounds on average before you should change it.

C rating - You need a sufficient C rating to give the gun the power it needs. mAh x C equals the maximum Amps. So in your example, 2000 x 15 = 30 Amps maximum. In this example, your stock gun will be absolutely fine. The higher this limit, the easier it is for your battery. You don't want to work your battery to the limit all the time. The more headroom, the better.

Alrighty then. Cheers for the info. I think it'll be a while before I have a go at the drum.

First off, sorry about the Necro.

Secondlly Google shows this thread with the most, if not All the Very detailed info for this. figured i'd toss my .02 cents in.

Anyhoo Picked on of these up in the US. (Wisconsinite here).

Pretty much can confirm the same issues with Ken.

However, My hop-up chamber was cast correctlly, and noticed if you used the stock cylinder, and positioned it, while closing the Gearbox (prior to cranking down the screws). it will align straight. Aftermarket Cylinders are .5mm too long and don't sit correctlly in the shell.

Also. Core Air-seal PTS Nozzles will work over the CNC'd Red Nozzles and Seal Well with many buckings. (using a Madbul Black bucking, with a Solid Plastic Nub). aside from shimming and regreasing the lower, Keeping the AGM Blue belled motor for now/Gearset. Its pulling 24 BPS on 15c Li-po Firefox Super Power 1250 mah Packs. and the Drum, once Fed. Keeps up without skipping a beat with 1.2v NIMH rechargable AA's. HOWEVER... i forsee the JST connector being a weak-point, Just like on my old Ares Stoner 96. Ill run it till the pins fail, then rewire it to bullet connectors. Oh.... and the Audio Report. Its unlike any other LMG out there. its not that Canvas tearing sound, but has a unique pitch to it.

Back off the topic of a X-mas land 42 (with the tolerances being right). Its quite simple to work on, and for those on the fence. Think of it more of a parts kit for what your getting. With a new nozzle, piston, and a field rated spring (for your area) and some TLC. It will offer quite a bit, where CA/A&K LMG's trail behind in the range department.

Just curious, is it possible to fit a box mag to this for an MG3 look?

Anything is possible with enough money. :)

Hello

I picked up a boneyard MG42, turned out to have a broken tappet plate and is missing the stock (anyone have a spare?). After fixing it up it works fine, but one of the drive gears in the magazine has a few teeth shorn off. Has anyone run into this?

Ken, what did you use for a gearbox when you upgraded the motor?

Thanks
Mark

Hi Mark, I'm not sure what you mean by gearbox. In either case of the gun gearbox and mag gearbox, I used stock gearbox shell. The internals of the mag's gearbox are stock.

Hello

The mag gearbox- one of the little plastic gears has some stripped teeth that cause the magazine to stop feeding under load. I'm trying to figure out a way to fix...

I don't think there is an easy way as I don't think it'll be easy to find an exact replacement. You can try 3D printing or just buy a new magbox.

get a cheap AK drum adn harvest the parts from that

Thanks- I don't know anything about them, are they battery driven? What's the best one to get?

cyma and yes battery driven

So it's confirmed that they use the same guts?

I think the biggest issue with the magazines are the plastic gears- any jam or misfeed and they are likely to strip- two of them are bad in the magazine I have.

Looks like the best price for a new CYMA mag is about $48 at airsoft megastore.

Interesting solution- check out what he did with the mag-

http://www.bingoairsoftworks.com/mat...ne-conversion/

here's the inside of one of the AK mags, don't see why it would not work with a little modding.

http://www.popularairsoft.com/review...-drum-magazine

looks at least a little more robust than what is in there to begin with.

hop up
 

so i'm sure you guys noticed that the hop up on this gun sucks the drop on my bbs is bad at pretty short distances. is there any better hop ups that will fit with little to no modification? or any other remedies like just increasing the fps or changing the barrel? thanks ahead

Mine works pretty good with .25 and .28, nothing that I've had to poke at yet.
What weight are you using?

You could install a new hopup rubber or put in a better nub?

I agree, I run .28 in mine, it shoots long and straight .. stock Hop

I have this one,enjoy it from august 2014. My mg42 has following: 525 fps, ~1200 rpm.
11v battery,high torque motor. And this stuff i have without changing barrell=)
P.s. also i made custom upper gearbox for higher fps than 525 and custom hop-up chamber for good compression. And i use airnozzle from G36 (25 or 26mm).
If someone interest in this way, i can write a normal review for this stuff.
There is no comercial in this post. =)

I am actually interested to see what you did with the hop-up. This is a project I've put on the back-burner but before I did I was not happy with the stock unit.

Back to the broken magazine gear issue- I ended up using the guts of a dual motorized double MP5 magazine. The gears are several times larger than stock. I was hoping to be able to use the sound activated feature but it did not work right (think I need a new sensor). For now it works fine in normal "on" position.
An added bonus is the mag has it's own lipo battery so the entire assault magazine is self contained. Also made a tripod AA mount out of an old movie camera tripod.

I still need to find a rear sight assembly, can't justify spending $80 on e-bay for one though.

I want to show few photos of my own project. Upper gearbox part and hop-up chamber.

Upper gearbox part. There is d16t aluminum alloy, made by cnc machine tool. Front side is thickened by 3mm. The groove for the cylinder is made for bore-up set - 70mm. External dimensions of a detail correspond to the basic sizes.
http://cs623917.vk.me/v623917631/33cda/cHQXGplzHvw.jpg
Upper gearbox part with internal parts
http://cs627531.vk.me/v627531631/19114/BOqpzwrx2YM.jpg

Hop-up chamber. D16T aluminum alloy. There is the ledge for an insert in gearbox, the hop-up chamber is executed so air nozle it was possible to establish less then basic 29mm, i set nozle for G36 (25.5 - 26mm).
In my basic hop-up the part for connection with gearbox is removed, as a result of the first experiments =)
The entrance opening for a platform of giving of bbs ("square platform")is made with the minimum admission by the sizes. As a result it turned out to avoid leak of air in this connection.
http://cs623925.vk.me/v623925946/48f24/U8lcJqeHZAs.jpg
http://cs623925.vk.me/v623925946/48f38/yAtu2QF_sHk.jpg
As it looks in assembled form. There is the first version of upper gearbox.
http://cs622621.vk.me/v622621946/62f12/e3TBboKHZag.jpg

There is a link to my "video" (may 2015) with firing MG42 with stock motor. I changed my M135 spring to M170 in video. I shoot more than 2000 bb during test (considering out of video tests). It was fine work during short turns and long lines of shots, no troubleshoting with upper gearbox part after test and through test. Sorry for non-english video, i want to make a copy with english text.

https://www.youtube.com/watch?v=yqCO...tailpage#t=158

I would like to answer any question. If someone want the same stuff to have in own AGM MG42, I can make the offer by rules of this forum.
With best regard, Siegfried
Belarus, Minsk.

That is freaking amazing. 8O

Hello Ken Tsui
Maybe your experience here can help me.
I'm working on an airsoft version of the M56 smartgun.
I will use an AMG MG42 replica to do so.
But my problem is the pistol grip with the motor inside.
It will stick out of it, not cool.

http://imageshack.com/a/img921/899/Hi9Vw5.jpg

My idea was to replace the MG42 gearbox with an A&K M249 one.
Do you think it can fit in?

Hi Cain, I do not have an M249 so I do not know if it will fit, but I can provide some measurements of the MG42 if you think that will help.

Thank you kentsui :)
Any measurements would be of great help.
Lenght, width and height of the inside where the gearbox sit will give me an idea of the empty space I can use to fit it in :)
If you could add the measurements of the MG42 upper part of the gearbox, it would be perfect :)

Here are the M249 gearbox measurements:

http://imageshack.com/a/img923/3879/8TxEZU.jpg

http://imageshack.com/a/img923/5213/y5Zlkm.jpg

http://imageshack.com/a/img923/1993/vkAuGw.jpg

http://imageshack.com/a/img924/9120/ugDxB4.jpg

http://imageshack.com/a/img923/4152/rFkaSb.jpg

My apologies. I keep forgetting about the measurements for the last few days. I will try to remember to do it tonight.

Well, I finally took some measurements. Let me know what else you need; I wasn't sure how much detail you want.

http://i1165.photobucket.com/albums/...4-13-38-01.png

25.6 mm is the width of the gearbox
200 mm is the length of the gearbox
47.2 mm is the width of the gearbox with the extension brackets installed
40.2 mm is the height of the gearbox



http://i1165.photobucket.com/albums/...4-13-38-07.png

22.4 mm is the width of the rectangular opening
38.8 mm is the approximate depth of the receiver. Note that the corners of the inside are chamfered. I'm guessing about 1-2 mm radius.
120.4 mm is the length of the rectangular opening, not including the round notch.
50.7 mm is the inside width of the receiver
1.3 mm is the approximate height of the raised screw holes, from the inside wall.


There is a small gap between the gearbox and the receiver walls when installed. It's not an error in measurement.

I would be very interested in getting a C&C hop up and the upper shell. I posted in your video but I have not heard anything back.