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Posted: 11/19/2002 8:15:30 PM EDT
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Hey guys, hopefully someone can help me, help a friend. My buddy has a brand new factory assembled AR-15 (I'm not naming manufacturer, because I don't want this to turn into a shoulda bought Colt/Bushy/RRA, etc. thread). Now always but occasionally, as in about 3 or 4 times in 30 rounds, his rifle fails to go fully into battery. The locking lugs seem to be engaging (or at least partially engaging) but you can see the bolt carrier is about 1/8" from being fully forward. Now there doesn't seem to be any rhyme or reason as to when it does this. 20 and 30 round USGI mags, and U.S. made Thermold(it didn't like the Thermold at all). S.A. battlepacks, Q3131A, TAP, and even tried the dreaded Wolf. Sometimes the first round from a mag, or any along the way. the worst part is that unless you visually check the bolt through the ejection port after every shot you don't notice that there is a problem until you pull the trigger and all you get is a click of the hammer falling. And when it does this it is VERY hard to get opened up again. even to the point he has had to "kick start" it a couple time. I've told him this thing is an accident just looking for a place to blow up and not to shoot it until we get this figured out. I should also note that it has been back to the manufacturer once when it was first bought for the same problem. It was returned to him as fixed, and although it will somewhat run now (it wouldn't cycle a single round before because it was so tight) it still isn't right, so let's skip past the "send it back" line of thought. Well, does anyone have any ideas? All help is appreciated. TIA, Dirk P.S. He is considering just buying a new complete upper and swapping, but doesn't want to do this unless he knows it will fix the problem. |
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mags would by my first guess. second, since it is a new rifle, clean it good. check the detent spring in the buttstock. also look at the bolt. do you see any heavy scratches? a new upper might not solve the problem. switch out yours with his. also check the gas system. watch the chamber when he shoots it. you might see whats goin on there. try the simple things first. later lojack |
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1. Check headspace - may be too tight. Manufacturers are not always honest about this! 2. Does bolt carrier and bolt work freely with no round present? Apply LOTS of CLP and try again. Criteria is that with muzzle down at 45 degree angle, upper and lower separated, charging handle locked forwar, carrier flush with back of upper - bolt should fall and lock into battery (on open chamber) when you release it. Chrome chamber? If not, why not? MAtch chamber? They are tighter. Chamber CLEAN? A little JB bore paste or tooth paste on a tight fitting patch spun by a drill for a min or less can really clean things of crud. Flush and clean all of the abrasive BEFORE shooting! Look for burrs or crud on bolt lugs or in barrel extenson. ONE bit of brass is all it takes to do this. If you drop rounds into chamber one at a time without a mag does it still happen? Have you tried loading SINGLE round in mags and verified bolt locks open EVERY time? Is buffer free moving? Have you tried switching uppers and both shooting to determine which 1/2 has a problem? Does bolt move smoothly and freely in bolt carrier? Have you washed WELL with brake clean and relubed with CLP? If you prefer other lube, fine. Use when the gun works. Start out with what Uncle uses. There's more but the above will get you started LOOKING at things! |
| I'm betting on the chamber being too tight, and it's hanging up when a max dimension round is the one going in. Can't tell without looking whether "too tight" is the headspace or the actual diameter of the round. Have him save any round that hangs up, and after he gets 5 or 6 of them, put them all in one mag and try to fire. If all of them (or all but one or two) hang up, then you have to assume too tight a chamber. |
If this happens with several different types of factory ammo I'm guessing the rifle's chamber is too tight/short/out of spec. I had this problem recently in 308 due to reloads that I had not properly sized but the same thing could happen with good factory ammo if your chamber is too tight or not enough headspace. Try removing the magazine to eliminate that. Load rounds manually and see what happens. |
If I had bought this rifle new and had these problems, especially after being sent back to be repaired, I'd be pissed. This is a problem the manufacturer of the rifle should be fixing. It sound like you should be talking to the head of the service dept. or someone higher up in the company to express your dissatisfaction and potential safety issues. Remember, the squeaky wheel gets the grease!
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Thanks for all the help. After reading the responses and talking him through things on the phone, I'm leaning towards a chamber that is just a little on the short side. Rounds don't seem to hang up when pushed in by hand (i.e. chamber to small diameter) and when it does "hang up" and not go into battery it is a bear to open, which leads me to believe that the bolt is wedged up trying to force a cartridge that is too lobg for the chamber into place. He is going to contact the manufacturer again and see if they won't take care of him. BTW, it is not brand new. He bought it new, but it has about 500-700 rounds through it. It has done this since day one. Thanks again, Dirk |
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do not be too quick to call it a tight chamber..., i once had experience with a slightly bent gas tube..., it was hanging up inside the carrier key.., the theory was that a round one time went up & hit the gas tube, thereby bending it just enuff to cause the boltcarrier not to fully lock up......, might not be, but check it any way........ |
Well, if you read back through the original post you will see that the rifle isn't mine, but then having spent a few years at Pope I don't really expect you to be able to read.  Hooah!! lol To update everyone my buddy has contacted the manufacturer and is in negotiations to get things taken care of. Hope to post more about the results when I know more. Dirk 2AS "Lancers" "if we can't drop it, you don't need it" |
OOF! (right in the gut). That hurt...  |
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