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Posted: 10/6/2015 11:22:57 AM EDT
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I built a new lower using an 80% lower and an Anderson lower parts kit. Had a TNS gas piston kit on it when I first built it and didn't have any problems. When I installed an Adams Arms piston kit, I started having problems with the bolt not going fully forward and even when it did, it wouldn't fire on the next round unless I cycled the bolt. the few times it did fire after cycling, it doubled. I immediately thought I'd messed up drilling the trigger and hammer pin holes and got them out of alignment, allowing the hammer to follow the bolt so I took the parts kit out of that lower and put them in a factory lower and ended up with the same result. The only thing I've done to the hammer and trigger was polish the contact surfaces. That's all I do with an AR build until after I've shot a few hundred rounds through it to see how it wears in. The 7 lb+ trigger pull didn't indicate a minimal sear engagement.
Any ideas on this description? Could it be a mismatched hammer and trigger or a bad disconnector? I thought that was supposed to keep the gun from doubling. |
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Quoted:
Is the wide side of the disconnector spring seated down into the trigger? Ditto, and with the trigger untouched, what is the free gap between the disco sear hook and the back hammer sear when you over cock the hammer past the disco hook. 
The free gap between the two with the trigger untouched should only be .001" to .003" (about that of a piece of paper) and if the free gap is wider, may need to remove metal from the front/bottom of the disco itself, where it seats against the top/front of the trigger to time the disco correctly. This will allow the disco to cam forward at its rest position to close the gap to the correct spec. |
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