Is powder residue on should & neck a safety issue?

[Gene]

You are loking at the powder evidence on the case shoulder, but you cannot see the barrel chamber, and the problem may lie there. I once had a factory rifle with an oval shaped neck (it was not properly chambered); cases came out with neck soot. Take the gun to a smith and have him scope it. This may solve your problem; in any event it should be done.

 

[Geno22]

I didn't see any buldge just above the band, I would say he is not to hot.

 

[SakoShooterSD]

I am just learning specifics of reloading, but form what I have learned, it sounds like the gas is escaping around the neck (which I think is normal). The problem is the gas shouldn't make it down to the shoulder because the shoulder should expand and seal off those gases inside the chamber at the time of detonation. That may not be a whole lot of help only to say that my 7mag doesn't get the gas all the way down the shoulder. Good luck.

Thanks, CRNA.
I think the neck should be free from fouling, too (It is also intended to form a seal with the chamber) though I think it is less surprising if/when it shows some powder residue. I believe the shoulder sees pressure before the neck does (and for a longer duration), so it has a better opportunity to expand and form the seal.

The more I think about all this, the more I'm inclined to think this is happening because the brass I've been reloading has been worked too much in each cycle (using FL dies which were pushing the shoulder back 0.008") and the powder in my latest recipe develops lower pressure than maximum.

I would like to try annealing some of the case necks, and repeating the recipe, though I've never done any annealing. It looks like something that can add more variation if you don't do it right, and I don't really have $325 to spend right now on a nice annealing system.
So, maybe I'll just buy some new brass, and start neck sizing only (and get my FL dies set up to do just a "minimum shoulder bump" . . . of about 0.001 or 0.002")

Anybody have an opinion on Norma brass?
I've been using Nosler, and would like to stick to the same brand . . . but everybody seems to be out of it at the moment. I found one place which seems to have Norma, though . . . and it seems to be about the same quality as the Nosler, maybe even a little better.

 

[SakoShooterSD]

You are loking at the powder evidence on the case shoulder, but you cannot see the barrel chamber, and the problem may lie there. I once had a factory rifle with an oval shaped neck (it was not properly chambered); cases came out with neck soot. Take the gun to a smith and have him scope it. This may solve your problem; in any event it should be done.

Very interesting! Thanks, Gene.
I'm inclined to try a hotter load first, or maybe try annealing the case neck & shoulder.

How much should I expect to pay a smith to scope/measure the chamber?
Sounds like it may be expensive.

Also, it seems that, if that were the root cause of this, then I would have seen it on all my loads.

 

[SakoShooterSD]

I didn't see any buldge just above the band, I would say he is not to hot.

Not too hot.
I was purposefully being conservative on this one.
Earlier, during some load development work, I identified two powder charges with the Retumbo which produced good groups. This was the lighter load.
I chose this lower powder charge because the groups seemed to change less around that point than around the higher charge. (group size is less sensitive to variation in powder charge at this lower charge)
Also, the velocity seems very good at about 2965 fps, which is on par with the fastest velocities listed for the maximum charges for various powders listed in the Barnes manual, so I didn't really think I would see any issues with the pressure being too low.

Again, I am leaning towards work-hardening of the brass being the culprit in all of this.
As soon as I can get some new brass, or gain some confidence in my annealing ability, I will repeat this load and see if the shoulders still come out cleaner. I will also likely try higher charges of Retumbo, and a couple of loads with IMR 4831 which has been very good in this gun.

 

[bigngreen]

Retumbo is notorious for sooting necks, even sometimes with a hot load. Everything I load it in will soot the necks to some extent, the shoulder should not be sooted. If it's a light load ramp it up and it should come of the shoulder but the neck still may soot no matter how hot you go.

 

[sureshot300]

Do you get the same results with the blackened necks shooting new brass vs. resized brass? That may tell you something.

Also, I used RL-22 in my 7MM Rem Mag a few yrs. ago. I shot the tightest groups in my life with 175 Nosler Partitions going 2860 fps. Used Rem Brass with Fed 215 Primers.

Don

 

[joe0121]

that can be a early sign of high pressure. For what it's worth Best group ever out of my .300 win mag was with a pretty warm hand load the left powder on the case neck. No issue with case extraction but took a lot of force to run them through a full length re-size. Now I neck size, and annealing the case solved the issue.