G&P Sentry (M4) Problems

First and foremost, I'm going to say, I am not opening this weapon nor do I intend to do my own work on it nor have I now or previously opened this weapon.

Here is the problem. I have a G&P Sentry, a short M4 style weapon, that doesn't fire quite right. On semi-automatic, it functions flawlessly. On fully automatic, it will go from firing normally, to shooting 30 ft, so getting jammed, to firing 3 BBs out at once, to firing normally, to getting jammed, then 30ft, etc, so and and so forth. The fully automatic function is very sporadic. When I look into the hopup chamber and fire on semi, I can see that the air nozzle retracts all the way, however when I fire on fully automatic I can see that sometimes it comes all the way back, and sometimes it ends up fully forward, or 3/4 the way forward. I don't know if that has anything to do with it. If anybody has any idea what this problem may be, or has any prior experience with such a problem let me know. I have had the gun worked on by the best, and it seems as though its so close to being fully functional, but its not there yet.

Also, don't tell me to "lol get a new gun its junk", I'm not doing that, don't suggest it.

Probably a tappet plate issue.

Maybe a tappet plate issue.
Edit: AH Josh beat me to it.

Bring it to me I will get you squared away. It's probably an ownership problem.....

Rhino wrote:Bring it to me I will get you squared away. It's probably an ownership problem.....

Paul Breaks guns by looking at them. Remember the Play-doh incident?

with your skill why not just throw bbs at people?
high kill rate and no gas or battery costs

^Lol, that never happened! Ryan, I'll bring it in to you. I do want to say, I tested it in my driveway today, didn't touch or disassemble anything, just loaded up the mag and wanted to see how it performed.

but this isnt your gun?

It is my gun...

Ah my bad I thought the first post said you didn't own it. Yeah it's now progressed to an ownership problem