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Posted: 7/6/2012 12:33:15 PM EST
Hi, just went to the range after some recent upgrades and had two double feeds in about 15 rounds. Because I just made a few changes to my AR I'm not sure where to start.

Problem:
Case not ejecting, causing a double feed. Upon inspection, the case was fully in the breech and could only be removed by shoving a cleaning rod down the front end of the barrel and forcing it out. Upon inspection of the casing, one side of the rim was ripped off (see pic), presumably by the extractor. Again, this identical problem happened twice in about 15 rounds shot.

Rifle:
S&W M&P15- Just changed the barrel and gas system from a 16 " carbine to a 14.5 mid-length from Ranier Arms with a pinned and welded Battlecomp 1.5 muzzle device. Barrel is Ranier's Cold Hammered Forged model.

Ammo:
Shooting BVAC .223 55 grain once fired brass. I was inclined to think it was the ammo but I've already fired 500 rounds before I made the barrel/ gas system change and never had this problem happen.

Potential Causes:
Ammo? Again, I fired off about 500 before the changes with no issues. Gas system? Barrel? BCG? I did check the extractor on the bolt and it appears to be functioning properly.

Thanks in advance for your help. I have a 2-day tactical carbine course in two weeks and would hate to be having problems like this or have my gun down altogether.

http://i1104.photobucket.com/albums/h326/matt_koch1/case.jpg
Link Posted: 7/6/2012 1:44:46 PM EST
Link Posted: 7/6/2012 2:06:06 PM EST
Thanks for the reply. Yes, first few shots were with just single round and bolt did lock back properly, no issue there.

I did not clean it first with a brush, but will do so now and hope that is it.

I've read on some other posts that some barrel chambers come in " tight " and need some breaking in.
Link Posted: 7/6/2012 3:11:06 PM EST
[Last Edit: 7/6/2012 3:12:01 PM EST by Dano523]
Link Posted: 7/6/2012 7:28:47 PM EST
Link Posted: 7/7/2012 4:58:41 AM EST
Thoroughly cleaned chamber with brush and CLP, bought two new types of ammo and will go back to the range today to test. Will report back when done.
Have not changed anything else like BCG, buffer or spring.
Thanks
Link Posted: 7/7/2012 3:27:31 PM EST
Update, went to range today and fired 60 rounds. 20 Remington 55gr , 20 Remington 45 gr JHP, and 20 BVAC once fired brass.

Fired 59 rounds with all casing ejected, and the LAST ONE got stuck in the chamber, failure to eject, just like the last ones.

Starting to think its a combination of tight chamber and soft brass on the BVAC ammo.
Link Posted: 7/7/2012 5:54:05 PM EST
Scrub the chamber very well. Polishing may get you want you want. YMMV
Link Posted: 7/8/2012 2:34:05 PM EST
Scrubbed and polished chamber really well and NO more failure to eject! Shot about 60 rounds of various types of ammo at the range today and no more ripped case rims!

I am drawing the conclusion that the new barrel just needed the chamber to be broken in through a mix of polishing and just running a few hundred rounds through it.

Thanks all for the help.


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