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Posted: 6/22/2009 8:24:53 AM EDT
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Rifle has roughly 360 rounds through it and on Sunday I was experiencing the trigger not resetting about once every 15-20 rounds fired (various .223). 80% of the time I could get the trigger to reset by playing with the fire selector. Two of the times it locked up I cleared the rifle and pulled the upper to find the hammer cocked and still no trigger reset. The instances where I cleared the rifle and continued, the round pulled from the chamber had a very slight firing pin strike on the primer which originally lead me to believe the hammer was following the bolt carrier (is this even possible?) but the cocked hammer/no reset when I pulled the upper has me confused. I did pull the fire selector thinking there might be something under it but it was clean. My next move is to pull the trigger and hammer and make sure thier clean.
Also, I can NOT replicate this manually. Not sure if this matters but I'm also in the middle of an ammo issue. I was shooting some XM193 two weeks ago and the was blowing primers. LGS still isn't sure if it's an over pressure (no other visible signs) or ammo issue and I've since switched back to .223 (side note, when I started shooting the 5.56 I put in an H buffer, could this be affecting the cycling of the .223?) More than likely it will be going back to S&W, these little gremlins are pissing me off, and since its six months old they can figure it out. Sorry for all the questions, Tom |
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My guess is that your trigger problem is related to your ammo problem. If you are blowing primers then there is a good chance that something fell into your lower found it's way into your FCG.
ETA - http://www.jobrelatedstuff.com/core/topic.html?b=3&f=66&t=448584 |
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Quoted:
The instances where I cleared the rifle and continued, the round pulled from the chamber had a very slight firing pin strike on the primer which originally lead me to believe the hammer was following the bolt carrier (is this even possible?) but the cocked hammer/no reset when I pulled the upper has me confused. I did pull the fire selector thinking there might be something under it but it was clean. My next move is to pull the trigger and hammer and make sure thier clean. The light indentation is normal due to the free-floating firing pin. Yes the rifle can malfunction in a way that the hammer follows the BCG, but this usually results in several slamfires. If you have verified that the fire control group is clean, lubed, and free from obstructions, it sounds like a bad disconnector (slightly out of spec), burrs on the disconnector or hammer notches, or a weak trigger return spring. I would give your FCG a good cleaning first. |
| Just had the same issue after some blown primers. I found a crushed primer in under the FCG and it was blocking the return of the trigger. My finger was strong enough to fire but the return spring couldn't overcome the primer cup. I flushed the lower but you couln't see the primer from above. I even had primers down inside the magazines. See my post below "TinMan2" |
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