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Posted: 1/24/2015 9:08:33 PM EDT
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Got back from the range a couple hours ago and my dad and I had an issue with his bushmaster. Only thing that is done to it is a bmc ch, everything else is factory.
We were attempting to sight in his scope and shot about 60 rounds through the rifle no problem. Then we loaded another mag and the first round would fire and then the second round wouldn't. The trigger wouldnt compress, almost like it was on safe, which is wasn't. I put my bcm bcg in it but the same thing happened. I google'd the problem at the range and actually found a thread on here where someone was having the same issue. Someone in that thread suggested testing the gun buy having it empty, pull the charging handle, pull the trigger and hold it in, pull the charging handle again, let go of the trigger and listen for a click. My dads rifle did not click. While I was doing this I found that the trigger was not going all the way forward and when I pushed it the rest of the way, the gun would fire no problem. So the first round fires, second round doesn't, if you pull the trigger back forward the rifle fires fine. Is this a mechanical failure due to dirtiness of the rifle or something else? The rifle probably has less than 200 rounds through it and this was only the second time we have shot the gun with no cleaning in between. I don't clean my rifles after every outing and have never had an issue like this. |
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Either a piece of a blow primer has found is way under the trigger, or the FCG parts are badly fouled, and need to be cleaned.
In either case, really need to pull the FCG out of the lower receiver get a piece of primer out, and/or, to clean the FCG parts and reinstall them lubed correctly. Lower receiver in hand only, hold the hammer back slightly, and use a punch to push out the trigger pin and remove the hammer. Use the punch and press out the trigger pin, and remove the trigger. If the selector if giving you fits getting the trigger out, put hard thumb pressure on the selector side of the selector flat, via turning the selector from safe to fire and back, should be able to walk the selector detent out of the selector groove and remove the selector from the receiver without having to remove the pistol grip. If you do remove the pistol grip to get the selector out, then make sure not to loose the selector detent pin in the bottom channel of the receiver. 
Now look for a piece of blow primer that is hiding around the top of pistol grip channel to remove it. Give the FCG a quick once over for any burs on the FCG that may need to be removed, 
Then put the FCG back in the lower receiver. As for a couple of notes, disconnector spring gets installed large coil side down into the back of trigger slot, and the hammer spring legs rest on top of the trigger pin. And if you removed the selector without removing the grip, the just use a pick tool to push the tip of the selector detent pin down back in it channel so you can get the face flat of the selector past it to reinstall the selector. 
http://www.ar15.com/content/guides/assembly/lower/ |
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Quoted:
Either a piece of a blow primer has found is way under the trigger, or the FCG parts are badly fouled, and need to be cleaned. In either case, really need to pull the FCG out of the lower receiver get a piece of primer out, and/or, to clean the FCG parts and reinstall them lubed correctly. Lower receiver in hand only, hold the hammer back slightly, and use a punch to push out the trigger pin and remove the hammer. Use the punch and press out the trigger pin, and remove the trigger. If the selector if giving you fits getting the trigger out, put hard thumb pressure on the selector side of the selector flat, via turning the selector from safe to fire and back, should be able to walk the selector detent out of the selector groove and remove the selector from the receiver without having to remove the pistol grip. If you do remove the pistol grip to get the selector out, then make sure not to loose the selector detent pin in the bottom channel of the receiver. http://www.ar15.com/content/guides/assembly/lower/pistolGrip.gif Now look for a piece of blow primer that is hiding around the top of pistol grip channel to remove it. Give the FCG a quick once over for any burs on the FCG that may need to be removed, http://i81.photobucket.com/albums/j226/Dano523/9425369358_4d5c87e150_o_zps31d6ac67.jpg Then put the FCG back in the lower receiver. As for a couple of notes, disconnector spring gets installed large coil side down into the back of trigger slot, and the hammer spring legs rest on top of the trigger pin. And if you removed the selector without removing the grip, the just use a pick tool to push the tip of the selector detent pin down back in it channel so you can get the face flat of the selector past it to reinstall the selector. http://img.photobucket.com/albums/v503/AR15forme/IMG_5660.jpg http://oi43.tinypic.com/2hd1kqb.jpg http://www.ar15.com/content/guides/assembly/lower/ Thank for the info man, I'll give it a shot. I've never take apart a lower so I am slightly hesitant but it doesn't look hard. |
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