AR15 issues

[SOFDC]

Background info: M1 Sales upper, 20 inch 1:9 twist barrel, 5.56 chambered and chrome lined

In the 500-600 some odd rounds of WWB and poly coated Wolf I have had two FTExes where the extractor has torn part of the rim off the casing, obviously there's no way to get it out without a cleaning rod. This has happened once with WWB, and once with Wolf, both times (seperate incidents) I was shooting fairly rapidly, strings of 2-3 shots followed by a 2 second or so pause before the next string, both times it happened after about 60-70 rounds.

There don't appear to be any rough spots in the chamber, nor did it appear especially dirty, all the same I cleaned and brushed the chamber out, is there anything else I can do?

This is the only problem i've had with the upper and it's got me stumped...

 

[NMshooter]

Maybe the extractor spring is weak, causing the extractor to not fully engage the cartridge rim. As far as I know you should not need any special parts like o-rings or Dfenders in a full length gas system, but you could try that if replacing the spring does not work.

Before you replace any parts, however, you might want to see if the extractor channel in the bolt has anything in it that might prevent the extractor from fully engaging. Also look at the extractor claw, make sure it is within spec.

Hope this helps.

 

[SOFDC]

Eh? Not engaging? Theres an extractor-width section of the case rim being ripped off when this happens. It's not slipping OFF the rim, its taking part of the rim OFF.

 

[Zak Smith]

Gauge the gas port to determine if it is oversized.

 

[Bane]

I have had the exact same problem on a few occasions with my M1sales upper when using Wolf ammo. Each time the problem was that cases were sticking in the chamber because of the dirty Wolf ammo. After a good cleaning the problem was gone. After a hundred to two hundred rounds of Wolf my chamber needs to be cleaned or rounds will start to stick.

 

[gamachinist]

If it happened after shooting Wolf ammo,I would think it was just a build up of the coating Wolf uses in the chamber,agravated by the rapid fire heat build up.

If it happened with the Winchester ammo,
After it had been cleaned from shooting the Wolf ammo,
I would suspect the chamber may be at minimum size or the headspace at minimum,perhaps because of a worn reamer that was just barely in spec.

Again,this would be agravated by the rapid fire heat build up.
Try making a chamber cast with cerrosafe and checking the size against SAAMI and 5.56 Nato Specs to see.

 

[NMshooter]

So the extractor is removing as much of the case rim as it engages?

In that case Zak probably has the answer, too much gas pressure slamming the bolt and carrier back harder than normal.

Not that the folks suggesting an out of spec chamber might not be right, either.

Can you post some pictures?

 

[FROCKDUTCH1]

I would suggest getting a go/no go guage to make sure your chamber/headspacing is correct. Then I would clean the heck out of it due to the varnish deposits that wolf ammo builds up in the chamber once you are up to "operating temperature". This stuff is so tenacious that I have had to remove it with a small torch by applying heat, then wipe, and then repeat until I have all of it gone. other than that, you can plug the barrel and fill with solvent/alcohol and let it soften overnight.

another thing to check is if the built up crud under your extractor is levering it into the closed position and not allowing it to flex. if so, you should remove the pin, clean well, replace the spring (cheap) and shoot extensively.

just my .02