So I just finished my first build the other day. It's an ar15 chambered in 300Blk. I am using both super and subsonic Remington umc ammo. I didn't think anything of this until one of the guys on the range mentioned it is a problem. The mouth of the casing is kind of bent in alittle bit. So instead of having a crisp circle it's a circle with a quarter of the circle being flat. I will post some pics in a few minutes. He was saying something is hitting somewhere which could cause the rifle to jam. Does anyone know what might be causing this problem?
Problem with AR brass
- Thread starter Balzer94
- Start date
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guthook
Grrr.
The case mouth is probably being smacked on the brass deflector. If so, no big deal. That what it's there for.
Use something to open the mouth back up. I use a tapered nail set punch and just push it into the opening. It rounds it out good enough for the dies to function like intended.
A tool like that is useful, especially if you pick up range brass that has been stepped on.
Use something to open the mouth back up. I use a tapered nail set punch and just push it into the opening. It rounds it out good enough for the dies to function like intended.
A tool like that is useful, especially if you pick up range brass that has been stepped on.
Russ D
Ultimate Member
It's normal. What buffer system are you using? It sounds a little over gassed.
h2 buffer i believe
![IMG_2694[1].jpg](/data/attachments/62/62535-4ffdde1f5878db652c0b385289049b61.jpg)
They look like ALL of mine.
okay thanks. the guy was just saying it wasnt a good thing. he did know what caused it but he said it wasnt good. just wanted to check
- Aug 17, 2011
- 26,177
Look at your brass deflector, I'll bet you $20 that's where it's hitting and bending the case mouth in.
My 300BLK did the same thing with factory ammo (sonic or subsonic), doesn't do it on my handloads though...
My 300BLK did the same thing with factory ammo (sonic or subsonic), doesn't do it on my handloads though...
Russ D
Ultimate Member
Totally normal.
Look at your brass deflector, I'll bet you $20 that's where it's hitting and bending the case mouth in.
My 300BLK did the same thing with factory ammo (sonic or subsonic), doesn't do it on my handloads though...
id bet you the 20 but id lose. i have noticed the brass markings there. i didnt think thatd bend the mouth but now im sure it is. hopefully starting next week i can start making some hand load. waiting on dies, chop saw, and some bullets
- Aug 17, 2011
- 26,177
I'd only make a bet if I was sure I was going to win.
With my handloads, I don't have the case mouth damage anymore, but they still deflect off the deflector (I believe the case head is smacking into it on exit), so don't expect to never have brass transfer on it again. But with a tried/true load, your case mouths should fare better.
I've found my happy spot with mine (finally, I did something right!!) and they're staying there.
- Aug 17, 2011
- 26,177
Even my cheap Lee dies pop those out w/out a issue, so your in good shape.
.223's a longer case, so there's not much room for rotation on exiting vs a 300BLK case, I very rarely had case mouth damage on .223 loads, but there was always plenty of brass transfer on that deflector.
.223's a longer case, so there's not much room for rotation on exiting vs a 300BLK case, I very rarely had case mouth damage on .223 loads, but there was always plenty of brass transfer on that deflector.
- Aug 17, 2011
- 26,177
Aside from my starting days, when I ruined 2 FL-sizer dies by not lubing enough (whoops), I've never felt the need to spend more than Lee's asking price for my needs.
Their 300BLK dies work well enough that I haven't thought about upgrading. If I was chasing maximum accuracy, then yeah. But I already get sub 2" groups with the Lee, so that's fine for my needs right now.
Their 300BLK dies work well enough that I haven't thought about upgrading. If I was chasing maximum accuracy, then yeah. But I already get sub 2" groups with the Lee, so that's fine for my needs right now.
Yeah I destroyed a sizer deprimming pin by not lubing enough. I got a casing stuck and tore the rim off the casing. I took the rod out and well melting the brass also melted the deprimming rod. Other than that I haven't had any problems. With the cleaner that I use for brass, it leaves the 9mm slick enough that I don't even need lube. Those all use lee dies
- Aug 17, 2011
- 26,177
Every mistake is just another lesson learned IMO, they're bound to happen at some point. 
