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Page AR-15 » Troubleshooting
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Posted: 12/31/2006 5:25:27 AM EST
 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, quality USGI and C products
Gas Rings tight in carrier
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
Link Posted: 12/31/2006 5:46:27 AM EST
[#1]
I'm sure someone with more knowledge than me will chime in but, at this point I'd swap out the gas tube with a brand new one.  It's cheap and would rule out any issues with that period. you mention crappy handloads which makes me think dirty and some obstruction of the tube. The only other thing I can think of is if it's been doing this since it was new is to check to make sure the frontsight base gas hole and the gas hole in the barrel line up correctly.

good luck.
Link Posted: 12/31/2006 5:50:23 AM EST
[#2]
Your problem is most likely in the FSB/gas-port area...

Since you cleaned the gas tube, that should be clear...
Link Posted: 12/31/2006 6:41:13 AM EST
[#3]

Quoted:
Your problem is most likely in the FSB/gas-port area...

Since you cleaned the gas tube, that should be clear...


Is there anyway for me to check what you mentioned with out takeing it off  ? The FSB/ gas port area that is... Thanks WarDawg
Link Posted: 12/31/2006 9:18:02 AM EST
[#4]
Pull the handguards and look for black soot accumulating near the FSB.  Other than that also look to see if the FSB has possibly shifted position and perhaps not fully aligned with the port any longer.  You will see more with the guards removed.
Link Posted: 12/31/2006 9:28:50 AM EST
[#5]
Link Posted: 12/31/2006 6:46:51 PM EST
[#6]
Link Posted: 1/1/2007 4:45:46 AM EST
[#7]

Quoted:
Spray can of BreakfreeCLP,
Chamber brush,
30 cal mop.
Cleaning Patches,

Upper comes off the lower, and the B/C stripped.

On the upper, a Good shot of CLP down the gas tube, the chamber/bore, in the barrel extension.

ON the B/C , everything shot with a good coat of CLP, including a burst down the key.

ON the lower, pull the Buffer and spring, and a good shot down the inside of the receiver extension.

Now leaving the upper for last, wipe everything down to remove any old caked fouling/ dried grease.

ON the B/C, again a good wipe down, then relubed.

On the upper, using the chamber brush, get the chamber as clean as you think you can, then using the 30 cal mop soaked in CLP, spin it in and out of the chamber to get the last step cut of the chamber clean.  Using a few Q-tips and more CLP, get the dried crud out of the barrel extension.  Now one more blast of CLP down the gas tube, then get the bore dry and clean.
Note: leave the CLP in the gas tube.  If left in place, but the time that you go to shoot the rifle, it will have dissolved all the fouling in the tube, and this fouling will just be blown back into the gas section of the B/C and blow out of the action.

Simply, you need to get the rifle de-fouled from storage and CLP allowed to soak will loosen and remove all the old fouling/crud that has dried in place.


Dano we have exchange ideas on this rifle in the past.  I had just remembered shooting the shit ammo years back and then putting the rifle up. I always clean my rifles before the safe gets them but maybe the carbon has set up in the port/tube for atleast 9 years without the rifle being shot again. I will try the breakfree aresal ( thats what I clean with anyhow ) in the tube and carrier key area and let it sit for a few weeks. Thanks again WarDawg
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