Hard extraction with CMMG 11.5" upper

[Scotter260]

I had my SBR out yesterday and had a couple of extraction/ejection issues but I chalked it up to old range mags based on what appeared to be bolt over ammo failures. I did have a couple of double-feeds but due to what I believed was a mag issue I attributed these to the mags as well. In these the first cases were stuck but upon closing and opening the bolt manually they came out. Ammo used was 100 rounds of polymer Wolf, with which I've never had problems. I've had the upper since purchased new in 2007 and have not had problems with that either. The upper currently has approximately 2,500 rounds through it. The upper was clean upon going to the range and was cleaned when I got home.

Today I took it out again with new magazines and some laquered Barnaul ammo. Ran like a clock through the 80 rounds I brought along. Loaded up some Prvi 75 grain Match and only got through 5 rounds before the 6th round stuck to the point I had to bang the casing out with a cleaning rod. The case rim was also "smeared" where the extractor attempted to grab it.

Does this sound like an extractor/spring issue, ammo issue, or "Dude, you've got a crappy upper" issue?

Right now my plan is to purchase some spring and o-ring kits from Bravo to get by and in the mean-time save up my pennies for a BCM 11.5" upper.

Thanks for any info.

[Iraqgunz]

I am pretty sure that you have a tight chamber because it is CMMG. You may also want to change or check the ejector spring and extractor spring as well.


I had my SBR out yesterday and had a couple of extraction/ejection issues but I chalked it up to old range mags based on what appeared to be bolt over ammo failures. I did have a couple of double-feeds but due to what I believed was a mag issue I attributed these to the mags as well. In these the first cases were stuck but upon closing and opening the bolt manually they came out. Ammo used was 100 rounds of polymer Wolf, with which I've never had problems. I've had the upper since purchased new in 2007 and have not had problems with that either. The upper currently has approximately 2,500 rounds through it. The upper was clean upon going to the range and was cleaned when I got home.

Today I took it out again with new magazines and some laquered Barnaul ammo. Ran like a clock through the 80 rounds I brought along. Loaded up some Prvi 75 grain Match and only got through 5 rounds before the 6th round stuck to the point I had to bang the casing out with a cleaning rod. The case rim was also "smeared" where the extractor attempted to grab it.

Does this sound like an extractor/spring issue, ammo issue, or "Dude, you've got a crappy upper" issue?

Right now my plan is to purchase some spring and o-ring kits from Bravo to get by and in the mean-time save up my pennies for a BCM 11.5" upper.

Thanks for any info.

[markm]

So the PRVI got stuck after firing steel ammo?

I agree that being a CMMG, the chamber isn't likely to be right. But I've read of issues of chamber fouling from steel cases (which don't expand the same as brass) causing brass cases to stick.

[Scotter260]

Thank you both for your replies.

I recall there being issues mentioned about going from steel-cased to brass and I may have even had an issue with it myself with a long-gone Bushmaster carbine but I don't recall having to worry about this with this particular upper.

That BCM upper is sounding like a better option with each passing second.

Thanks again guys.