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Posted: 9/20/2015 5:47:39 AM EDT
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So I've come across a problem that I don't what's going on nor does a quick google search.
An ar15 fires on the trigger reset every few shots, never a set amount of shots. The history of the rifle; the rifle was bought new, never fired but peviously owned and has had thousands of rounds through it without a hickup. Take it out to the range after several months in the safe and it starts to fire upon trigger reset every few shots. I have visually inspected said freinds rifle and see nothing abnormal; no spent primer, not to dirty, no excess lube... just a normal FCG. Dry firing recreates similar results. Hold trigger down, pull charging handle and release, trigger reset click, pull trigger firing ping click times 2-7 times... then randomly... pull charging handle and release, trigger reset and right away firing pin click without pulling trigger. I am puzzled at whats going on. |
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Try charging the carbine with the trigger held back.
After you let bolt return forward QUICKLY release trigger If hammer stayed cocked, Repeat test while SLOWLY releasing trigger. If hammer dropped, You have a timing issue. The Disconnector is too far backward. Make sure the disconnector pivots all the way forward. If it did pivot all the way, then, stone a small amount, the front/bottom of the disco where it seats against the top/front of the trigger. You want the disconnector to pivot closer to the hammer. |
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Oh yeah. One thing more.
if it failed the above test, Wear, or a botched trigger job could have caused it. PSA and Geissele sell enhanced triggers that can end your grief $34.99 - $59.99. The enhanced trigger, and a Joe Bob trigger screw $14.95 , and JP yellow springs $10. 49, will give you a first rate GI trigger. For a very low $$$ amount. Now would be the time to upgrade ! Joe Bobs sells all of the crap. 
Email me if you cant get it. I have new take off FCG's that I would trade you. |
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Disco timing was questionable when new, and now that the FCG has seen a few throusands rounds, the disco free gap is too great instead.
So step one, pull the FCG and clean all the parts with CLP, then reinstall the FCG with the parts/pins lubed on the heavy side with CLP as well. If needed to pull the FCG and put it back in, http://www.ar15.com/content/guides/assembly/lower/ Now with all the parts cleaned and lubed, cock the hammer back without touching the trigger and watch the distance of the back hammer sear as it passed by the disco sear. The free gap between the two should be in the .001" to .003" range (thickness of a sheet of paper). Here is a disco that the free gap is too large, the disco needs to be re-timed, since again the two sear edges should almost kiss as the pass by each other with the the trigger untouched. 
So if the Free gap between the two is too large on the rig, then the disco will need to be re-timed. http://www.ar15.com/forums/t_3_66/656984_AR_pistol_problem.html |
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