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Posted: 7/26/2012 5:27:23 PM EDT
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I have a co-worker who isn't a member here - he recently bought a piston AR and is having an odd trigger issue, one I've never heard of before.
50% of the time the gun works perfectly. The other 50% of the time, the trigger won't reset. He fires a round, keeping the trigger depressed, and the gun cycles. Empty goes out, fresh round chambered, no problem. When he releases pressure on the trigger, the trigger doesn't reset fully forward; it goes halfway. The gun is non-funcational at this point. He can gently nudge the trigger forward and it will reset; pulling the trigger then fires the gun normally. He cleaned the gun before the first range trip and afterwards. If he removes the upper and manually cocks the hammer and pulls the trigger, everything works fine 100% of the time. It's like something odd is happening under recoil. The gun is brand new and still under warranty - my co-worker has already contacted the manufacturer, who will gladly fix the problem if he returns the gun for service; my co-worker is just wondering if this is an easily-fixed issue he can take care of himself. Anyone have a suggestion of things he can check? |
| Has he taken the fcg out and checked to see if everything was installed correctly and there isn't debris in the bottom of the lower? Could be improperly installed trigger spring. Could be something like a blown primer rattling around in the fcg area of the lower. Could be improperly installed disconnector spring or the disconnector could be improperly timed/out of spec. |
yeah i would wager the hammer spring is improperly installed or faulty.
http://www.ar15.com/forums/t_3_4/226782_Assemble_your_own_LOWER__UPPER__FREE_FLOAT__TRIGGER__GAS_BLOCK___Step_by_step_instructions_.html |
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He needs to pull the FCG, clean the parts, then reassembly the parts back in the lower with all the parts CLP lubed, including the hammer and trigger pin, and even the FCG channels.
While he has the parts out of the lower to clean then, also have him run his fingernail down the disco and back hammer sear edges. If an edge bur is found on either sear, use a fine stone to remove the bur without dulling the sear edge. As for sending it back, not really since at some point, he is going to have to learn to pull the FCG to clean and lube the parts, and even may have to pull the parts to get a Blown primer piece from under the trigger out. Here is the basics for pulling the FCG out of the rifle, and regarding spring, disco spring goes large end downward into the back of the trigger slot, and the hammer spring coils should be with the legs on the bottom side of the receiver and coming back with the legs resting on top of the trigger pin. Lastly, when he removes the pistol grip to remove the selector, there is a spring in the top of the pistol grip in a channel, and a small detent pin just above the spring in the receiver channel. He needs to be aware of these parts so he does not loose them. http://www.ar15.com/content/guides/assembly/lower/ |
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