Soot on the neck

[abunaitoo]

I've been testing on my T38 Arisaka. 6.5x50.
Lyman 140ge. I4198, 2400, I4227.
I reloaded the brass five times, and figured it was time to anneal the necks, before they split.
After I annealed them, I starting getting lots of black soot on the necks.
I thought annealing is suppose to make the brass softer.
I thought softer neck would seal better.
I wasn't getting the soot before annealing.
Didn't seem to affect the accuracy any.
Why am I getting the soot now?????

[MUSTANG]

Possible that before you annealed the necks the tension was such that pressure was building up more rapidly before the boolit was released; resulting in a more rapid neck expansion and less gas blow by on the neck before it sealed. After annealing, the pressure before boolit neck release was less and you got more gas blow by before the neck sealed.

[waksupi]

Try increasing powder charge a bit.

[abunaitoo]

I tried a cheap neck size. Put a washer over the shell holder before sizing.
Soot was much less. Some cases had none at all.
I did notice a few cases had blow by at the primer.
When I seated them, they all felt tight going in.
Cases have been reloaded many times.
Maybe their just worn out.

[HangFireW8]

Please share your loads. Mild loads can have primer blowby, because pressure is not sufficient to expand and seal the primer cup in the pocket.

Also, were these cases reformed, or original?

[243winxb]

Soft necks let the bullet move sooner at lower pressure. Takes about 15,000 + psi to expand necks.

Light loads expand the case body outward. This pulls the shoulder back, away from the chamber. The head to datum measurement becomes shorter , as does trim length on fired brass.

[abunaitoo]

6.5 Arisaka, 266di 140gr GC, I4227, 2400, I4198.
All around 13.0 to 15.0.
No soot before annealing.
Did the annealing because I didn't want the necks to split.
At a higher change, accuracy starting to go.

[GregLaROCHE]

Are you crimping the cases? If not try it. Might make a difference.

[robg]

heavy crimp should up the pressure might solve the problem

[abunaitoo]

They are crimped, but I'm using the crimp on the seating die.
Haven't gotten around to making a Lee FC die yet.
I guess, maybe, I made the neck to soft.

[GregLaROCHE]

The crimp from the seater die should be enough, if it’s adjusted to give the max possible. That’s all most people used to use a while back. You may have to look elsewhere to find the problem. Do you have other cases that you haven’t annealed to try. Maybe they’re hard to come by. I have a 7.7 jap that I haven’t shot for over thirty years. I remember back then it wasn’t easy to find bullets or brass for it. Good luck. Hope you get it figured out. Let us know what you come up with.

[Petander]

Possible that before you annealed the necks the tension was such that pressure was building up more rapidly before the boolit was released; resulting in a more rapid neck expansion and less gas blow by on the neck before it sealed. After annealing, the pressure before boolit neck release was less and you got more gas blow by before the neck sealed.

I'm quite sure this is what happened to me with 458 Socom.When the brass softened up after some reloads it started sooting. New brass with high neck tension was shooting clean.

Faster powder solved the problem, now the pressure builds up fast enough to prevent leaks in the very beginning.

[GregLaROCHE]

Today I was as working with a friend to lower the charge in a 308 with a silencer. We were trying to get it to shoot sub sonic and still recycle the next round. We were reducing the amount of powder in an uncrimped case and then we started to get carbon on the case necks. I crimped the cases and the carbon fouling stopped.

[abunaitoo]

Could be the shells are just worn out.
I noticed on some of them, I had leakage at the primers.

[243winxb]

leakage at the primers, time for new brass.

[David2011]

Crimping assures that the powder starts to burn before the bullet moves. If the primer pushes the bullet before the powder builds pressure the bullet could be in the barrel before the powder starts burning. Blowback is inevitable. You’ll also be rewarded with bigger groups due to the inconsistent ignition.

[abunaitoo]

Accuracy is good.
I have a tuff of dacron over the powder.
But I did before I annealed.
Only thing different is the necks were annealed.
Maybe I shouldn't have done it, but I didn't want the necks to split.
Reloaded over five times before annealing.
It's funny, but when seating the primers, it's tight going in.
I did change primers.
Went from CCI to Remington.