Posted: 12/31/2006 6:23:19 AM EDT
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Same story , Have an AR that is haveing short stroke problems. EVERYTHING checks out. EVERYTHING. Swappped ammo ( quality stuff ) While it did function better with the Q3131A it still acted up. Its a Colt preban 1986 rifle. Less than 600 rnds through it. I have checked everything yall have suggested. Im about to part swap this rascal. The ejection patern is great .It piles the brass up 6ft away at a 5 oclock position if 12 noon was the muzzle . It has the style Bolt carrier with the UnHooded fireing pin. It normally don't jam but won't lock the bolt back and one or two rounds pre 30rnd mag might not get back far anough to strip a round for the next shot. Rifle Colt A2HBAR 20" Factory rifle. List of things I checked out : Mags Gas Rings Gas carrier key staked and tight Gas tube aglinment with carrier key No binding in the buffer tube Swapped to A good batch of Q3131A .No go .Ran better but not solved No binding of carrier sliding in upper Lubed properly, Breakfree,or FP 10, or Mil com. I cleaned the gas tube with Gun Scrub by shooting it down the tube for 10 seconds. Along time ago I did something stupid. I tried some reloads in her and she malfuction terrible. I threw the rounds away and put the rifle in back of the safe for many many years. Could the power residue from these shitty rounds , while sitting up so long cause this and hardened up to wear Gun scrubber and the blast of quality ammo going threw the gas tube not blow the it out and be acceptable. Guys Im reaching deep and about to go to a Palm reader on this one. Im not claiming to ever be an expert but I know AR's and this one has me mind boggled. Thanks for hearing me unload. WarDawg |
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WarDawg, I'd try polishing the Chamber, its possible that there is some crud that just isn't coming out with hand tools and gun solvents. You'll have to do a little searching but what I've found to work the best is to use a Dremel with Flexshaft. a buffing pad small enough to fit the chamber and some Jewelers rouge. It may take several times to get it nice and shiney, once polished. get some of the foaming bore cleaner and fill both the bore and the gas tube with it and flow the directions on the can. be careful about getting the foaming cleaner on the upper, it may harm the aluminum. HTH, Jason |
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Are you getting a lot of blow-by at the FSB? If yes replace the gas tube. Did you pull the buffer and spring out and clean or just push on it to see if it moved? Inspect the inside of tube? Swap bolt and carrier with another rifle? [SCRATCH HEAD]If all else is tight and free moving,I have no idea.[/SCRATCH HEAD] Next would be a AR-smith to check it out.....Red you out there?  GLOCK-23 |
| Yep, although I am no expert, I would start with a THOROUGH cleaning of the chamber, bolt lugs and also the buffer tube. Make sure its got some lube, and then look at swapping the gas tube or FSB. There might be a blockage in any of those areas. A little spider may have made a home in there over the years. |
The one thing I didn't do was swap carriers. Good idea. I have pulled the buffer/spring and cleaned the tube and lighly lubed. Guys my rifles are very well maintained. I mean very well maintained. This isn't a lube or cleaning problem. I inspected the chamber with a scope type light and solvented it down and chamber brushed it very well. The rifle is extracting and ejecting the rounds very well. It just short strokes. The carrier would go back 1/8th of an inch further it would be 100% . Just not quite anough to lock back and one rnd out of a mag it will not strip a case and chamber. Not an Mag issue. I do appreciated the replys and suggestions. Where to get some of that good Federal /Lake city ammo ? WD |
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Wardawg, This may seem odd, but there was a guy down at one of the Uwharrie shoots a couple of years back who had a nice Bushmaster rifle that was consistently short stroking. I cannot remember exactly who it was who told him what to check, but it was recommended to him that his bolt actually had too much lubricant on it. He was shown how to disassemble it and the bolt was wiped down, replaced in the carrier, one drop of lubricant was applied through the carrier key opening and the whole thing reassembled. The rifle immediately began to run flawlessly after that. Seems wrong, but somehow it fixed his problem. If this doesnt' do the trick, is there any way to clean the gas hole that's drilled through the barrel, without having to completely remove the FSB? Might have some jacket material or carbon deposits blocking this? |
| Thanks for the reply . I have lubed light and I have lubed heavy. Ive been dealing with AR's since the mid 80's. Im not expert .But fully understand the hows and whys of the system. The rifle in question is a new 1986 rifle LOL. Only 600 rnds through her. The only thing Ive ever replace was the extractor spring with a GOLD Colt spring. It's something borderline. Im thinking about just putting a good quality set of gas springs and a new gas tube on her. That would be fairly cheap and if it doesn't correct the issue ,they ones I taken off is still listed as good to go in the repair parts box. Thanks again for the replys, WarDawg |