M4 Blowback Methods

[Boo-Sabum Ben]

Hello guys,

At the moment I have 2 of Cymas blowback mp5s. I was wondering, does anyone else make an M4, that has a blowback system, that runs in the same way?

The blowback is powered by the bolt slotting into the top of the gearbox, and being dragged back by the piston, then spring forward after it.

Would be nice to be able to swap to an M4 by just switching the gearbox over when I fancied it!

[Bachelarius]

Re: M4 Blowback Methods

Both the TM Recoil and the Modify Tremors is basically the same, albeit housed in the buffer tube. The new APS Hybrid boxes work the same way though, but without the weight, just the flappy fake-bolt. I believe the Top shell ejecting M4 functions in a similar way as well.

I think that the G&G pneumatic method is probably the safest (gearbox-wise) implementations of the system out there, as there is no risk of the piston clashing with the recoil unit.

[Boo-Sabum Ben]

Sorry if I confused, they're not recoil MP5s, just blowback. So simple bolt moving back and forth.

The plan was to simply take an M4 and drop all the Internals in, and find one that used a similar blowback mech, and use that. Thinking about it though the bolt assembly from a recoil M4 may actually work in a standard aeg receiver...

[Bachelarius]

Re: M4 Blowback Methods

I've had a peek inside the CYMA MP5 before, only actual difference between it and a standard V2 gearbox is the hole in the top and the weird little hook on the top of the piston (and the selector plate/air nozzle, if you are after fitting the MP5 box in an M4). I'd imagine that if you swap out the selector plate, the gearbox should slot straight into an M4, you just won't get the blowback effect, unless you customise the bolt cover to interact with it.

Take a look at how the new APS gearbox works. Slightly different interaction method, but identical principal:

As for something that directly interfaces with the CYMA mp5 gearbox, no idea on that one. I am 99% sure that a regular gearbox will interface with the CYMA though (again, possibly not the nozzle, definitely not the selector plate), if you remove the bit on the bolt that hooks into the gearbox.

[Boo-Sabum Ben]

Cheers for that! I might look into the aps solution and see if there's any interaction there.

I primarily wanted to just swap the gearbox over if I fancied an m4 for a bit, then swap back to an mP5 when I fancied. I've been spoiled by recoils and blowbacks so that's a must have feature for me nowadays!