Special Purpose Rifle (SPR) Mk12 mod1 Replica w/ Pro-Win Gearbox Install!

[ILLusion]

It's already seen field action once for a milsim and it got 4 kills that day. And I totally demolished a sign. Even knocked it right off the post it was hanging from.

Hopefully I'll get a chance to bring it out more often before it starts snowing.

[damage]

Brian!! we have the same. well almost :-D

[ILLusion]

I was just working on this gun, figuring out some annoying issues with the Pro-Win gearbox and remembered this thread, so I thought I'd revisit it to update on the new Pro-Win 7mm issues I've encountered:

The cylinder head is not supported properly in the gearbox. It actually sits too far forward. Because of this, the air seal is inconsistent, and even worse, the piston sits too far forward in battery. Because it sits too far forward, the sector gear does not engage it properly. This was why the PGC polycarbonate piston that came with the gearbox snapped so fast where it did. It took about 3000 rounds before I noticed a tiny big of strange wear on the custom Prometheus piston I installed before I finally figured out what the real issue was.
The reason why I started to look at this specific problem, was because of the primary issue with the cylinder head sitting too forward: Because it sits forward, it doesn't allow the tappet plate to pull back as far as it should. Because of that, the air seal nozzle is also not cleared enough out of the chamber to allow proper feeding! By around the 3000 round mark, my gun was so inconsistent with feeding (or completely HALTED feeding), that it forced me to look inside.

The solution I've come up with is to place a shim at the front of the cylinder head, that pushes it back in to the cylinder far enough to allow proper engagement distances. I'm currently using just a piece of cardboard to test whether it works, and yes - this has fixed the issue. I now need to come up with a different shimming material that's a bit more consistent. The thickness needs to be approximately 2.5mm thick and you need to find a way to fix it to the gearbox to prevent movement in to the path of the tappet plate.

Another issue that's developed that I haven't explored yet, is when in semi-auto mode, if I pull the trigger up to 7/8ths of the trigger pull length, I get full auto. The firing will only release when I either a) let go of the trigger b) pull the trigger completely. So the only way to ensure just ONE shot being let go, is to pull the trigger quickly. I'll be looking in to this issue shortly.



But back to the SPR:
I assessed the value of all the parts that I put in to this piece... and... well... let's just say I shed a little tear when I rang up the final number.

Well over $2000.

That doesn't even include the optics, bipod, batteries or BBs. *cries*

[Godlyspartan]

Curious Brian, does the Bore up kits work properly under 420ish fps

[Cassius]

So....basically the Pro-Win gearbox is not necessarily the best gearbox there is?

I'm saying that because I'd love to get that one gearbox where you rarely worry about it no matter the cost.

[Ace of Spades©]

I think the new 8mm Pro-Win addressed these issue and is a more 1337 ninja black/gray

[deep in the bush]

My,

what nice work Brian. Its a joy to see your work.

miigwetch

deep

[ILLusion]

Originally Posted by Godlyspartan

Curious Brian, does the Bore up kits work properly under 420ish fps

Yeah, it does. I tested between the bore-up kit and a regular kit and saw no difference in velocity, consistency or rate of fire. But at the time, I was testing with a Systema M120S. I think that since that spring is the minimum spring recommended to start using a bore-up kit, and 590mm is also the longest inner barrel you can use with a full normal bore cylinder, the performance of the two setups overlapped at that point.

Originally Posted by Cassius

So....basically the Pro-Win gearbox is not necessarily the best gearbox there is?

I'm saying that because I'd love to get that one gearbox where you rarely worry about it no matter the cost.

I never said that Pro-Win isn't the best there is. In fact, I think it's the best at what it does. It comes down to what qualities you consider to be "the best." If you're looking for a gearbox that you can easily install, then no, Pro-Win is not the best. It's probably the worst in that regards. But if that factor is something you hold high, then just get a Systema drop-in gearbox. Don't even have to open it up and worry about shimming.
But that wasn't the point of this project. The point was to get the BEST full-featured performance out of this gun platform.

I still think the Pro-Win detachable gearbox is the best gearbox you can get for a standard Marui (clone) AEG because of all the added features it provides on top of the added durability.

Does it have issues? Yes, it does. Installation is difficult and skill is required.
The gearbox has always been marketed with a very clear warning:
"INSTALLATION TO BE DONE BY PROFESSIONAL ONLY."

I concur with that statement - if you're adverse to performing hard modifications, STAY AWAY from this gearbox. If the idea of grinding up your brand new metal receiver scares you, STAY AWAY. This is what I would consider to be an advanced installation.

But once this gearbox is installed properly from the beginning, it will provide for you an extremely solid and well performing platform.

[Raysaaark]

I have 2 of the 8mm versions that have been sitting on my work bench for some time in one stage of completion or another, and I will agree with Illusion that these things are a hugh pain in the ass, but once done properly they make you giggle! I do believe that the issue with the tappet plate has been addressed with the second release of it, but I would have to say that it is perhaps not perfect quite yet. I would also agree that the PGC Piston that they have with the Version 2 of it, is crap. I stripped the first 2 rack gears on it with just the M80 spring in there after about 100 shots.

Shimming is in my opinion one of the hardest things to do for it internally (reciever mods aside) as it is a very persice gear box. I just wish they included some more info on the CD that ships with it regarding, well, every aspect of the thing. The pictures they have for what needs to be done to the recievers leaves a little something to be desired. And not including any info on Guarder recievers is annoying.

And as for the Version 2 of it being leet Ninja black... It is not that nice. To be honest, I would much rather it be some funky color like the nice neal one, or some of the prototype colors they went through. not this bland deep gray that it is. I would have really loved a deep red.

But I will say one thing. 8mm Bearings just keep going. Your gears seem to spin forever on these things!

Now if only I can get enough cash to put both of them togeather, then I will be happy.

[Dynamo]

got a prowin 8mm box in my VFC HK416
ILLusion is right about it being a pain to install (was up till 5am).
now that i have it all set up and running smooth, it sure is one hell of a sweet gearbox.
there is still some tweaking i need to do but damn, can it ever spit out BBs.
400 round hicap emptied in about 10sec on 8.4v with the M80 spring.
the gears are really quiet, but the motor and antireverse latch make quite a racket.
im running a set of systema tourque-up helical gears.
next step, pinp it out with a crap load of usless accessories.

[Caped_crusadar]

to what extent would the modding be to a CA m15?

and it says by professionals, how pro do you need to be?
ive only been in it for half a year or so, but i know my way around a gearbox, and im pretty handy with tools, do you think i could to it?

the only place i can find the 8mm version is this place in china, do you know anywhere closer to the us?

[Bowers]

Originally Posted by Caped_crusadar

to what extent would the modding be to a CA m15?

and it says by professionals, how pro do you need to be?
ive only been in it for half a year or so, but i know my way around a gearbox, and im pretty handy with tools, do you think i could to it?

the only place i can find the 8mm version is this place in china, do you know anywhere closer to the us?

thank you for the necro

[Caped_crusadar]

Originally Posted by TCSF-Bowers

thank you for the necro

what?

[TokyoSeven]

Originally Posted by Caped_crusadar

to what extent would the modding be to a CA m15?

and it says by professionals, how pro do you need to be?
ive only been in it for half a year or so, but i know my way around a gearbox, and im pretty handy with tools, do you think i could to it?

the only place i can find the 8mm version is this place in china, do you know anywhere closer to the us?

Ignore the necro call, its better you post in an this original thread than create a new one.

Well it appears you reside in the USA, there are many retailers that you can find online. However there isnt anything wrong with ordering from asia either. If you can stand the wait that is. Its not just about knowing your way around a mechbox when it comes to prowins. Their an a little more difficult to handle than most and in most instances from what I understand you will have to modify your reciever to install the mechbox. If you are knowledge in the use of tools and are prepared to do so I would say best of luck and good on you. If you are not comfturble with this then I would recommend staying away from this project as it could get costly aquiring a new reciever everytime you screw up.

[ILLusion]

Originally Posted by Caped_crusadar

to what extent would the modding be to a CA m15?

and it says by professionals, how pro do you need to be?
ive only been in it for half a year or so, but i know my way around a gearbox, and im pretty handy with tools, do you think i could to it?

the only place i can find the 8mm version is this place in china, do you know anywhere closer to the us?

Should be about the same amount of modding on a CA gun as it is on any other receiver.

As for how pro you need to be... well, you need to be able to figure out all kinds of trouble shooting issues. Ask yourself:

- Can I use a mill?
- Do I even have access to a mill?
- If not, do I have the rotary tools available to perform the kinds of modifications an end mill can do?
- Can I figure out feeding issues?
- Can I figure out piston alignment issues?

If you answered yes to most of those questions, then you can do it. Knowing your way around a gearbox simply isn't enough to install the Pro-Win gearbox.