MP7 Gas efficiency Problems
Posted 12 April 2013 - 03:01 PM
Dytac enhanced recoil spring
Ra tech enhanced recoil system
Ok now the problem: This MP7 refuses to finish a magazine even on semi automatic. About 30 shots in the bolt no longer recoils enough to load the next bb. When the enhanced recoil spring is replaced with the stock recoil spring the mp7 BARELY finished the magazine. Additionally after the bolt stops recoiling or the magazine is empty, manually dumping the mag's gas reservoir shows that there is plenty of pressure left. This problem manifested with all 4 of my 40 round mags. I'm not sure whats going on at this point. From what i understand these mags are supposed to hold enough gas for 1.5 to 2 magazines. Prior to this the gun worked just fine with the enhanced spring...
I think the problem may be either a worn hammer spring or a worn hammer, but i've heard reports of neither producing a problem like this... I do have a 150% hammer spring lying around but im not sure if installing this will address the issue. Thanks for any feedback!
Posted 12 April 2013 - 04:23 PM
It appears that the bolt is not traveling very smoothly. Manual cocking of the mp7 does not feel smooth and sometimes the bolt even locks up upon release and does not return to battery. I think the increased spring strenght may be pressing the hammer up on the bolt but im not sure how i would fix this. If anything this aggravated the problem
Edited by lorddave551, 12 April 2013 - 04:41 PM.
Posted 13 April 2013 - 09:37 PM
Posted 13 April 2013 - 10:57 PM
Edited by lorddave551, 13 April 2013 - 10:58 PM.
Posted 13 April 2013 - 11:03 PM
Posted 14 April 2013 - 07:50 PM
However, i do believe you are right about the internal seal. After completely disassembling the bolt i checked the seal between the reddish plastic head and i found the seal to be a bit loose. I was able to slightly wiggle the piston head in the nozzle which im guessing is bad since this is supposed to be an airtight seal. I think you may be correct in saying this is the source of the issue. I had similar problems with a 4 yr old marui 1911 and an upgraded piston head solved the issue. Luckily, evike sells an upgrade part by pro arms so i'll pick that up in day or two and test it out. Thanks for the help and i'll keep you posted
Edited by lorddave551, 14 April 2013 - 07:51 PM.
Posted 14 April 2013 - 10:45 PM
Posted 15 April 2013 - 03:39 PM
Posted 15 April 2013 - 07:27 PM
Posted 16 April 2013 - 03:19 PM
That being said, another issue has popped up due to swapping out the stiffer recoil spring for the weaker stock one. In short, after loading in a new magazine and releasing the locked bolt, it fails to return to battery. Here's a picture of the problem. Notice the small gap between the bolt and frame. The bolt will also semi occasionally fail to return to battery mid magazine but again this is rare. The only way to get the gun to fire is to eject the magazine, recock and release the bolt, and then reinsert the magazine.
Heres a picture
Edited by lorddave551, 16 April 2013 - 03:24 PM.
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