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Posted: 6/14/2013 7:50:31 PM EDT
| I have a Core 15 M4 MOE piston gun. When I fired the first round, it failed to extract causing the next round fed from the mag to jam up. Once cleared the rest of the mag functioned fine. It happened one more time about 4 rounds into the next magazine. This occurred with 2 different types of factory brass ammo. The 2 pieces of brass that failed to extract each have a flat side on the rim of the spent cartridges giving me the impression that the extractor ripped the edges right off. I'm new to AR's but I've never experienced this with any other weapon in decades of shooting. I would appreciate any input on what I need to do to troubleshoot this. The bolt locks open on the final shot, gun is well lubed but twice in two mags leads me to believe this isn't a fluke. What should I examine first? |
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Being that bolt is locking back, we can run out under gassed, but instead, too much gas pressure getting to the action to cause the bolt to unlock too soon while the spent case has too much residual bore pressure locking the spent case to the chamber walls instead.
The good new, the rifle has an adjustable gas system on it, so just how far down have you dialed the gas system to try to solve the over function problem. Lets make this simple and just tune gas system like you would a FAL. Dial the gas system all the way down for the least amount of pressure back to the action, and with a single loaded round in a mag, charge and fire the round with the empty mag still in the well, and see if the bolt will lock back. Keep doing this single round test as you dail the gas system up for more pressure back to the action, and get a setting that will just lock the bolt back.. From here, go one more setting with a touch more gas pressure to call it set. This will insure that as the gun starts to foul up,you still have enough pressure to the action to cycle the rifle correctly. If you already have the gas system all the way down, and still running into over function problems, then time to get Moe on the phone. |
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