dented case! what the ****? Anybody seen this before? Should I be concerned?

[texascop]

Whenever the rifle chambers a new round from the magazine, if I don't shoot and unload, it always looks like this. New to 6.5, but not new to reloading, I've never seen this. The cases fire form out ok, but that has got to be shortening case life. Your thoughts....

[BluntForceTrauma]

Is it being scratched by the lug teeth of the barrel extension? (Whatever they're called?)

[37L1]

Could be coming from the magazine. Trying switching mags.

[VASCAR2]

I have had ammo do this with some reloads in my 16" Shaw barrel. The reloads were using 30 grains of CFE223 with 123 grain Nosler CC in a Carbine gas system. I thought the slower burning powder and lighter charge might be the culprit. I radiused the ejector and used other ammo with no issues. The lugs were hitting the top of the case as it was attempting to leave the mag. I figured the bolt didn't have enough momentum to the rear to get a good push on the top cartridge.

[texascop]

That makes sense, bolt lug strike, and if that is the case I would think changing the buffer to a lighter variant would be in order. I am running a heavy buffer at the moment.

[rickOshay]

Did that round chamber?

I've seen similar marks on cases when the mag was not locked in and moved down when the bolt came across. This caused the round to jam into the feed ramp and stop.

[Variable]

Yeah, the rounds aren't feeding quite kosher. The case shoulder is getting those dents from the barrel extension's lugs. That's the kind of thing you also see with the bottom round in a double feed situation.

I'm supsecting the magazine is mostly the issue, but radiusing your ejector button head would also likely help.

Try some other mags? The feed lips on the mag that is doing this might need tweeked to present the round at a better angle.

[Sputnik]

Is it being scratched by the lug teeth of the barrel extension? (Whatever they're called?)

That is what happened to me with my 5.56 BHW barrel build a few years ago. Mine would actually not feed until the BCG was pulled back and allowed to slam it home a second time. You could see the teeth catching the casing. I sacrificed a box of ammo and after about 200 cycles they finally chambered ok. A faster remedy may be to polish the feed ramps and the sharp corners of the lugs.

[tackdriver]

I swapped uppers with a member here a couple years ago and he sent me very similar pics, it was a factory AA upper. After a bit of back and forth we certainly to the conclusion was most likely the magazine. I sent him a different mag and he had no issues

[Variable]

That is what happened to me with my 5.56 BHW barrel build a few years ago. Mine would actually not feed until the BCG was pulled back and allowed to slam it home a second time. You could see the teeth catching the casing. I sacrificed a box of ammo and after about 200 cycles they finally chambered ok. A faster remedy may be to polish the feed ramps and the sharp corners of the lugs.

True. I was thinking that along with the radiused ejector (I like the "melt down" Paul does). I stopped short of calling for it though because I think there is still an underlying cause that needs fixed first. The rounds aren't presenting right on the ramp, and that's likely a magazine issue.

The polished feed ramp and radiused ejector help overcome sketchy mag geometry (great reason to have them!), but a proper mag should feed without them.

I guess the most harmonious conclusion is to adjust the mag feedlips, and then polish as one would prefer.

[NugginFutz]

My 264LBC was doing the same thing, back when it was having (under) gas issues. FTE, Double Feed, etc.

I re-aligned the GB, did an ejector spring mod, which cleared up the issue. I eventually added an adjustable GB so I could tame the cyclic rate without owning a library of different buffers.

[montana]

I just took my 4 Grendel's to the range today and shot over 200 rounds through all of them. I used 123 gr Amax, SST, reloads, and 100 gr. wolf steel case ammo and I have never experienced this problem. I have Alexander Arms and Lilja barrels with AA 30 round mags. All of my rifles have adjustable gas blocks and squared upper receivers. I always radius the ejector, polish the bolt face and extractor. I'm wondering if the tolerances in the receivers may be at fault. If the mag catch or any other tolerance is off it could be a cause ot this problem. What receivers are you using?

[REB]

I'm having the same issue, AA upper and AA mags. Mine is not a severe as yours. I am almost positive the mags are causing these dents.

[Adam Lilja]

I have this problem with AA mags and C-Products

[din]

I have this problem with AA mags and C-Products

Elanders or just the other AA mags?