Ejector Spring too tight maybe?

[OFP2651]

When using CBC 7.62x51mm the casing actually breaks on the rim where the ejector grabs it. I wish I took some pictures of the last time it happened, but unfortunately didnt happen. The break is obviously from the ejector because it is the same size. I just don't know if the ejector is too tight or if its something else; I know its not the ammo, because they worked in my last RRA rifle, the A2 version, but not my SO version. Just wondering if I could get some insight from people a little more educated in these matters than myself.

[unforgiven]

There are previous posts about heavy scuff marks to the brass on ejection.My SO did the same thing,and the mark varied with the type of round used.But the rim never actually broke and no one else has reported that problem.The ejector is VERY stiff I had the bolt on the counter put some CLP on it worked it in and out.Afer 800+ rounds it decreased but still scuffs once and a while.Get some pics together brother.

[texas30cal]

If it is the claw that pulls the case out of the chamber, it actually doesn't pull it out in all firearm types but you understand what I am talking about, then that is the extractor. Is it breaking the rim on the way in because it can't snap over the rim or is it ripping the rim off on the way out?. I had one ripping the rim off due to a rough chamber, it was not a RRA but have read about DPMS having that problem. The ejector is the small round spring loaded plunger opposite the extractor.

[OFP2651]

I dont think it is breaking them on the way in, I will definitely take some pictures if I shoot anymore of that ammunition, I have kinda separated it from my usual ammo stores because of that fact. I was getting some funny looks at the ranges when I was double feeding and having to punch out an ejected round.

[OFP2651]

I am headed back home to KS this week, and I am not taking any of that ammunition there, so it will be something like a month until I ever shoot the CBC ammo again.

[planeflyer21]

I'm not so sure about that CBC ammo.

 

A friend measured the fired cases he has, and they were 2.022"...a mere 0.007" OVER max cartridge length.  That would be one heck of a stretch for the first firing.

 

Measure your unfired cases, see how they measure.

 

Jon

[sketch]

I had some trouble w my lar using pmc 147 this week I had a light primer strike on my last round (always chk for open bolt!!!) re fired the round chk the bolt, there's my case facing 180 mashed neck first into the bolt face!! No joke I have the case and a witness. I did notice ejection was way up at 2 o'clock. My buddy says it was crashing off the deflector and the brass was about 3 ft pass the barrel in a nice pile. Hoping it was a phenomenon

[texas30cal]

I got about 50 or 60 damaged CBC's from my LGS, a case broke open and they got damaged by the pallet jack wheels and they were going to throw them in the dumpster. I pulled them down, sized w/out the decap rod, weighed the total powder and divided it out evenly, reseated, crimped some still had dents but firing took care of those. I will check to see how much they stretched. Just send me your CBC ammo and I will test it for you :))  :auto:

[unforgiven]

I think I missed it but what is CBC ammo???

[OFP2651]

^{It comes in a box like this.}

[unforgiven]

Thanks for the pic bro,I have not shot that.I think PSA was selling that.

[planeflyer21]

My EO shoots the CBC just fine...not sure why so many others have issues with it.

 

Jon

[OFP2651]

Like I said, it shot fine out of my A2 Classic, but not my SO, just confusing to me. When I get back I will probably give it a my gunsmith and see what he can do with it.

[Tripledeuce]

   An extractor ripping a rim off is indiditive of a hot load, or a rough chamber, or a gas problem.

   As a gunsmith, the first thing "I" would do is a through cleaning, followed by a bore scope check of the chamber, a chamber cast, followed by either a slight reaming of the chamber( my DPMS 260 chamber was slightly "out of speck" and to tight on the body, took a finger turning of the chambering reamer to bring it up to speck.  Then a chamber polish, followed by test firing with "good" ammo,then the CBC.

   Also, I would check the gas port size, and, if over gassed ,install an adjustable as block.

   I would polish and de-burr the extractor.  Not much, just a quick polish.

  I'm still learning AR's, but ,with 50 years of professional gunsmithing, this is here I would start.

   Respectfully

   Terry

[texas30cal]

Sounds like good advice, I don't have a scope or reamer so the first thing I did was clean it well then just looked at the chamber with a good flashlight and I could see the machining marks from the reamer, took the barrel out and polished with very fine paper on a wood dowel, I think it was 600 then 1000, but it did not take much to fix it.