Hey folks,
I'm getting soot blowback on my brass and seeking guidance on what to do to get it to stop (on the assumption that it is a problem).
Gun: Swedish Mauser (6.5x55) Carl Gustauf M96 (1912)
Powder: 45.4 grains of IMR-4831 (the Hodgdon data is 43.0 - 47.0c)
Primer: CCI Large Primer
Bullet: Hornady Interlock 129 gr seated at cannelure (COAL 2.920)
Brass: PPU with 3 firings (2 since annealing)

I fired 8 shots today, all with this load. The last 3 shots produced these soot patterns.
I've seen these before and with very light loads of H4831, and have even gotten dented shoulders. I assume this is a sign that the case necks aren't creating a good seal. Should I...
I'm getting soot blowback on my brass and seeking guidance on what to do to get it to stop (on the assumption that it is a problem).
Gun: Swedish Mauser (6.5x55) Carl Gustauf M96 (1912)
Powder: 45.4 grains of IMR-4831 (the Hodgdon data is 43.0 - 47.0c)
Primer: CCI Large Primer
Bullet: Hornady Interlock 129 gr seated at cannelure (COAL 2.920)
Brass: PPU with 3 firings (2 since annealing)

I fired 8 shots today, all with this load. The last 3 shots produced these soot patterns.
I've seen these before and with very light loads of H4831, and have even gotten dented shoulders. I assume this is a sign that the case necks aren't creating a good seal. Should I...
- Move to a faster powder like H4350?
- Move to a magnum primer when using IMR-4831?
- Re-anneal the necks and see if the problem goes away?
- Stop worrying about it?