2:45am Frustrations can't break 240fps w/upgrades

[Rabbit]

So I've received my TM Mp5sd6 completely stock firing at 230-250fps and after reading some of the forum posts about what to upgrade first I purchased these parts:

Prometheus Non-Linear Spring MS110
Modify 6mm Stainless Steel Bushings - Double Oil Channel
Modify Air Seal Nozzle - MP5 Series
Prometheus Air Seal Chamber Hop-Up Packing (Soft Type)
StormTech MAX Impact Polycarbonate Piston
ARS MASK Duo POM for Ver. 2

The first gundoc I had stop by successfully installed all the parts, however the prometheus hop up sleeve was sticking out slightly into the hop up chamber a slight bit but enough to cause numerous jams. On a limb we decided to trim a bit off, but quickly realized that this would ruin the air seal around the bb but by then it was too late. The hop up sleeve was then replaced by a systema one instead with no feeding problems at all. We kept the prometheus bucking in as well.

The major problem was that no matter what we looked at the fps did not raise at all. It remained at 240fps however it was a consistent result.

The second gundoc that stopped by figured it had to do with the compression. Upon looking inside the mechbox the modify mp5 airnozzle had broken around the bottom ridge and with no other parts on hand, the stock TM air nozzle was put back on.

The cylinder was also swapped out with the TM stock one and a Modify cylinder was put in. With testing the piston in the new modify cylinder the compression was AMAZING, however when the tappet plate was put on it quickly went to garbage.

After becoming frustrated with little options left we put the gun back together and again it was only firing at 230-240fps.

In the end non of us knew what was causing the issue but i have tried to describe this as best as i could - to the gundocs that stopped by to help out if you're reading this help me out if i missed anything

so, the most recent doc just left at 2:40am and its now 3am. hopefully someone can help me out.

I'm missing my bi-weekly game tomorrow because the gun is in pieces and its so late.

Help!


EDIT: Everything works 100% now. Im shooting roughly 310-320 with 25s. Lesson learned - do not trim the hop up rubber! ARS rubber was installed, fit perfectly. All other upgrades are perfect, compression is great. Thank you to everyone who helped out with replies!

[cjboi]

the parts you bought suck... like ARS MASK Duo POM for Ver. 2 and Modify Air Seal Nozzle - MP5 Series. Get the cylinder kit next time, so you wont have to buy the parts separately. If you wanna get modify parts, then get this (http://www.airsoftparts.ca/store2/in...oducts_id=1102). Get a better piston head and cylinder head (non-bore up, since your not using m120+ springs). Those two parts you got are garbage...

[Kos-Mos]

Your parts are fine.

But I guess you are still using the stock TM cylinder head?

If so, the brass tube can detach from the nylon head part, that will cause a huge air leak when the pressure comes high enough to push it.

I would install a complete cylinder kit, all from same brand. Modify and ARS are good brands.

With the parts you have, you will want to order a V2 cylinder head, either Modifiy or ARS MASK. Also order a new loading nozzle. You want a bearing spring guide too since the stock TM will wear down quite fast and cause a lot of inconsistency with you start to push higher FPS.

But my bet is on cylinder head.

[Rabbit]

The ARS Duo Pom is actually a set, cylinder head and piston head shown here:

[zone 69]

Only things I can think of with out seeing it for myself is.

A Bearing Spring Guide to fill the rest of gap left from the stock setup.

And to make sher your Hop-Up Chamber is staying seated when fireing.

And what wait of BB are you useing to test the fps, and is the hop-up off when your testing.?

[Rabbit]

Originally Posted by zone 69

And what wait of BB are you useing to test the fps, and is the hop-up off when your testing.?

Im using .25 BBbastards to test, each gundoc brought a chrono to test, results were the same on both.

[CDN_Stalker]

Air nozzle might not be meshing with the hop up unit properly.

[coach]

What inner barrel? Does the rubber sit tight? Could be the nozzle not the right length in your setup.

Do a compression test on your air chamber. Should get resistance once the piston head passes the port.

[Rabbit]

The inner barrel is stock, yes the rubber sleeve sits tight.

The compression test proved to be really well while holding it in your hands and blocking then end of the nozzle with your thumb, however once the tappet plate was put into place there was very obvious leakage due to it moving in and out of the cylinder with not as much compressed air.

[THe_Silencer]

Well it seems like it's not a cylinder problem. You can try swapping the stock cylinder head back in and see what happens. This may cause a ever slight change in air nozzle length which may allow it to mesh with the hop up properly. Or it may do nothing at all.

[RacingManiac]

Chiming in as a complete AEG idiot, one of my old KA M4 AEG, brand new out of the box, never shot over 220-240. I ended up removing the barrel nut and just reseated the hopup/inner barrel assy. and tighten down the nut and it was shooting 300 like it is supposed to. That was a stock KA. Not sure how the MP5 is made internally, at least from my M4 deal it looks like not having the the hopup mated correctly to the nozzle will do enough of a reduction in power.

[Rabbit]

I'll take a look at the hop up again to see if anything is going on.

Im pretty sure it has something to do with the cylinder tho, what i dont understand is why the tappet plate is affecting the air compression. All is normal when i hold it in my hands but when its placed into the mechbox with the plate on the piston just kind of pushes into the cylinder with less air compression.

My next step is to try the stock TM cylinder head with the mask pom piston head and see if this makes a difference.

My new modify air nozzle with the oring ended up breaking so i have to resort to using the stock TM air nozzle for now.

[Amos]

Originally Posted by cjboi

the parts you bought suck... like ARS MASK Duo POM for Ver. 2 and Modify Air Seal Nozzle - MP5 Series. Get the cylinder kit next time, so you wont have to buy the parts separately. If you wanna get modify parts, then get this (http://www.airsoftparts.ca/store2/in...oducts_id=1102). Get a better piston head and cylinder head (non-bore up, since your not using m120+ springs). Those two parts you got are garbage...

... The MASK piston head and cylinder head are the best ones on the market right now... I'm willing to bet you have zero first hand experience with them and are just regurgitating something you heard someone else say.

@Remy:

Sounds like you've got a hop-up/nozzle issue..

Did your techs check compression with the nozzle on?

Edit: Totally sounds like a nozzle compression issue, You're going to want a good air seal nozzle, and you're going to want to use a little bit of silicon grease on the outside of the airway on the cylinder head.

I'm not 100% sure on the TM Mp5 (so many different MP5 versions out there!!) but if it has a free-floating hop-up unit, did you remember to replace the spring that goes in front of the hop?

[Rabbit]

Well there was no spring in the hop up...so i dont think it was a free floating one. Although im not really sure what a free floating hop up means to be honest. The whole hop up itself is whatever the stock TM Mp5sd6 comes with, nothing has been swapped out other than the sleeve and bucking.

If there WAS supposed to be a spring, i did not see it when the first gundoc took it apart.

Im really not sure how much regular MP5's differ from mp5sds but i always thought they used the same type of internals

Another thing that was done with the hop up sleeve was a bit of the bottom was trimmed off, because when pushing the hop up onto the barrel with the sleeve it seemed to be bunching up, if we wouldn't have trimmed it, the end of the sleeve where the bb sits kind of sticks out into where the bb comes from the mag if that makes any sense. This is what was causing all the jams in the first place

[VooDooPeteK]

not sure if this hop up uses a spring or not but if it does its easy to loose as they are small.

take a look at the front of the hop up and see if there is a little nub. If so that is for the spring.