What the heck??

[stana]

Iv'e never seen this before. Dimples on the sholders. Load: 13 grs Red Dot 150 gr RCBS FP. Sized and lubed in lyman lubrsizer .311. RCBS green lube. Cases necked sized in Lee die. Photo shows fired cases and unfired rounds. the unfired were chambered to see if there was something in the chamber. Cases were never lubed and were dry and clean when fired. Whats going on? Thanks, Stan

[greywuuf]

The second one form the right..... that looks kinda square,( like the profile of a "stick" powder) I have had it happen once ( similar) when I got a grain of unburnt powder left in the shoulder of the chamber, I have never used red dot so don't know if the "kernels" match or not. Just guessing. Good luck figuring it out. the only way i think what I saw could happen was with a bit of headspace .. the cartridge moved back away from the chamber and the powder was ejected from the case, and as pressure built it trapped the powder under the brass. Not even sure it CAN happen that way, but I had a 5 round string of test loads that had kernal shaped dimples on them matching yours.

[badbob454]

beats me ??

[swheeler]

Anneal the necks. On firing the neck isn't expanding to seal and gas is leaking by collapsing/denting the shoulders.

[captaint]

I gotta go with Mr. Wheeler here. Sometimes, with underpowered loads, we get smoky brass and dents in the shoulder area. I would try a different powder and bump the load up some. Those dents, in my opinion are from gas blowing back. Let us know how it goes. Mike

[chboats]

13 gr of Red Dot in a 30-06 is not a low pressure load. It is no where near max pressure but not low pressure. The only place I could find a Red Dot load for a 30-06 ( I assume they are 30-06) is in the old Lyman Cast Bullet Handbook dated 1973. It lists a 14 gr load with a 150 Gr boolit will have a pressure of 35,000 to 36,000 CUP. Red Dot is fast enough that the pressure would probably peak before the boolit left the case. I would suspect something left in the chamber from the previous rounds.

Good luck finding the problem

Carl

[leadman]

If it is pressure causing this you could leave as much of the neck flare as you can to help seal the case.
I normally will leave a little of the flare on my old military guns since most of the chambers are on the large side. I think (hope) this helps center the case in the chamber.

Would not want to do this for a hunting or match load though.

[750k2]

Anneal the necks. On firing the neck isn't expanding to seal and gas is leaking by collapsing/denting the shoulders.

This is it - torch and a deep well socket spun in a hand drill dropped in water.
Clean the oxides off before loading

[Three44s]

Won't take much to re-run those dented cases after an annealing run.

Red Dot is the powder that taught me the value of inside flash hole deburring. I was doing milk toast lead loads in the .44 mag. Tested a few cases and I NOW do all my metalics that way .......... every last one of them.

Three 44s

[Jim]

This puzzles me. If the gas is leaking back behind the case neck and causing indentations, how can there be more pressure outside the case than inside? The pressure inside the case would have to be significantly less to allow the the indentations to manifest, right? Or not?

I've fired lots of low pressure rounds that showed the smoky soot around the case necks and down onto the shoulders. Never had the case indented like that, though.

And, by the way, water cooling annealed cases does nothing to improve or quicken the annealing. Brass is softened by bringing it to a given temperature, not by cooling it quickly.

[Ben]

stana:

Is it possible that your chamber isn't clean and dry ?

[greywuuf]

Cooling quickly is hardening anyway (and only on carbon steel as you say brass is unaffected) the reason for dropping in water is to prevent the heat from migrating beyond the neck and possibly softening the body, or worse yet the head of the case.




Homeland defense begins at home. I'm not there. Sent from a mobile device using a commercial app.

[Rocky Raab]

Jim, how that happens is this: high-pressure gas finds its way between the neck and the chamber as the bullet transits the bore. The instant the bullet leaves the bore, pressure begins to drop, but the trapped gas can't escape quite as quickly as gas in the bore, so there is a brief difference in the pressure outside the case compared to inside it. In that brief instant, the case dents appear.

If there is enough unburned carbon in that gas, it can also condense against the cooler chamber wall, causing soot in addition to the dents.

[nanuk]

Rocky: would less neck sizing and a fatter boolit help?

[Rocky Raab]

Hard to say, because that doesn't directly address the cause, which is hardened brass. The proper cure is to anneal those cases.

[stana]

Thanks for all the help. I had chambered loaded rounds then looked for the dent with out firing. When I showed those rounds to my son, he with his younger eyes could some denting on the unfired rounds, that I couldn't.

So I cleaned the chamber (and remembered extracting an unfired round loaded with 4895 some time ago when the boolit stayed in the chamber.) I found what was likely particles of compressed powder grains. problem gone. Thanks everyone. Stan.