Dented brass... is this a problem?

[geckocavemen]

Hello all, this is my first AR and I built the lower, which is a Bushmaster receiver with a PSA lower build kit and an H buffer. The upper is a PSA premium with FN barrel and mid length gas system. The ammo is Federal 5.56 xm193. Ejection is at about 4:00 and the brass flies ten feet or so.

I've done a lot of research and I don't think I have any problems but I wanted to ask just to make sure. The brass is hitting the deflector and getting dinged pretty good just behind the shoulder and I wanted to confirm here that it isn't over gassed. I've included pictures of the brass and also the deflector so you can see where the impact is occurring.

Finally, I'm still not entirely clear what the signs of over gassing are. I know if rims are getting ripped it's a sign but is there anything else?

[Onyx Z]

The rim of the case getting ripped off is not a sign of over-gassing. It's a sign of over-pressure ammo. Two entirely different things.

[markm]

Neither of those is a sure sign of over gassing. I'd try an H2 buffer at a minimum. I only run H buffers on BCM 14.5 middies because their port is a little smaller. An H2 or H3 will likely improve things. The shoulder dents aren't a deal breaker, but it'd be nice to minimize that. I can see some extractor claw marks on the rims, but with the lighting it's hard to see if they're excessive.

HEAVIER BUFFER!!!

[geckocavemen]

I'll get an H2 buffer and see how that improves ejection and the extractor claw marks. Almost went with that originally but decided not to at the last minute.

Just for my personal knowledge, what are some signs of an over gassed AR?

[markm]

It's really a feel thing. Rate of fire in full auto is a sure way to measure, but very few of us have that readily available.

Ejection patterns and stuff can give you an idea, but they're not 100% reliable. It sounds like you're not too bad if the brass is flying backwards.

[Lincoln7]

I recommend picking up an H3 buffer as it comes with 3 tungsten weights. In the event it doesn't run with that (my guess is it will run well) you can swap one of the tungsten weights out for a steel one making it an H2.

Or, since it's cheaper, buy the H2 and swap the one tungsten weight out of your H buffer to make the H2 an H3. Now, if only someone would sell the correct size tungsten weights...

[BufordTJustice]

I recommend picking up an H3 buffer as it comes with 3 tungsten weights. In the event it doesn't run with that (my guess is it will run well) you can swap one of the tungsten weights out for a steel one making it an H2.

Or, since it's cheaper, buy the H2 and swap the one tungsten weight out of your H buffer to make the H2 an H3. Now, if only someone would sell the correct size tungsten weights...

I agree. H3 at least. My wife used to run the OP's barrel in the 14.7" length and, before upgrading to a BCM, she ran a Vltor A5H4 buffer.

[geckocavemen]

Update: The weather finally cooperated and I was able to get out and try the H2 buffer today. It worked well and the dings on the brass were much less noticeable. Ejection was at 4:30 and the brass consistently flew about 10-12 feet. The bolt locked back every time as well. I was shooting Federal xm193.

I'm pretty happy with where its at now and gonna pass on an H3 for the time being. I'm afraid if I went with that the barrel would dip a little too much as the bolt returned forward. Below is a pic of some of the brass from today.

IMG_20150317_170103~2.jpg

[O3SKILL]

Looks like it's over gassed to me. Run some commercial .223 through it and I'd wager you won't see any more dents. I had the same issue with a factory Rifle I purchased firing Winchester M855....it was so over gassed and ejecting/extracting so violently that it was leaving massive dents in my brass from banging against the back of the ejection port. I was told to run a heavier buffer as a band aid, but decided to just send that humpty dumpty back. There is no reason a mid-length gassed Rifle shouldn't run properly with a H-buffer firing full power .mil loads. Unless of course the gas port is too big and it's getting too much gas.

[Iraqgunz]

I'd love to know how premium that gas port size is?