DMR problems

[Stomper87]

Alright, so i have a KWA m4 that I turned into a DMR. It's pulling an m170 spring with ease, but it wont fire bb's. They all jam up into the barrel, and eventually explode out the end. However, when I take out the mag, it fires one shot like it should. I have tried three different buckings so far, and they all do the same thing.

Also, it was an m4, but i put in an m16 length barrel. And yes, I did change out the cylinder.

[Star_folder]

What buckings have you used? Have you tried different mags? Have you tested your compression? When's the last time you cleaned your barrel? What bbs are you using?

[Skywalker]

Your hop up is turned all the way off, yes?

[Stomper87]

Well it turns out the problem isn't in the hop up, it's in the gearbox. For some reason, everytime I fire, the airnozzle sticks in the back position, instead of forward. Opposite of how it should be. Does anyone know how to fix this? Everything looks normal in the gearbox...

[Skywalker]

Lube it at the cylinder head, make sure the spring for the tappet plate on and not being hindered

[Star_folder]

That may or may not be a problem. Describe how you found out the air nozzle is sticking back? You could just be having over spin, which would start to pull back the piston and the tappet plate after a shot.

[Stomper87]

Yea, the problem seems more like an overspin, because when i put the gearbox back together, I can push the airnozzle back and forth. But as soon as i fire it, the nozzle goes back and stays back, untill i fire again.

[Star_folder]

Even so, overspin wouldn't effect the flight of a bb, or how it fires. The system should still be sealing, because it only fires when the tappet plate is at rest, only when the gears are in a certain position, and that position always has the piston released. Unless you've modified the gears something awful, there's no way the gun would fire with the air nozzle not pressed up against the hop up unit. Unless you've got a compression leak in your gearbox, it's not that.

Have you checked your bucking, it might be ripped. KWA 2GX buckings are great for stock fps, but probably won't seal with that M170 spring. You should consider picking up a new bucking, possibly an SHS Hard, or a Gaurder Hard. A Madbull red would work, but it'll be a heck of a tight fit in hop up chamber, especially considering it's already smaller than most.

Even if the bucking isn't ripped, I think it may still be your problem, that much air pressure will blow out the seal, and there won't be enough pressure to send the bb past the mound in the bucking, so it'll just get stuck. If your gun is jamming, and you don't hear the gears grinding on the piston, then you've got a compression leak somewhere.

[Stomper87]

I'm positive the bucking is not the issue. i have tried four different buckings now, and the problem isnt with the flight pattern of the bb. The problem is, I cannot push the airnozzle back. Its back as far as it can go, and only moves forward and then back after I pull the trigger. This is before I even put it in the gun. It's like the tapplet plate is moving in reverse. And I dont think its a compression issue, because the air it shoots definatly feels like an m170.

[Star_folder]

alright then, what bucking do you have in there now?

[Stomper87]

King Arms 80 degree bucking with SCS nub.