What this black soot on brass neck means?

bigHUN

bigHUN

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Over the summer I inherited some amount of hand reloaded amo with my new to me heavy 308 project gun.
Shoot all these amo for fun scoring and testing at mostly 200 and 300 meters with pretty decent results.
And in meantime collected my new tools so I can reload further diy. (I chose the LE Wilson die combo, so I can develop my own from a fresh start).
I noticed a carbon fouling - build up - on some of the now empty brass shells maybe 50-50%, on some more visible on some almost nothing. Unfortunately I didn't pay attention right that moment at the bench which shots were painting the brass the most.
Tumbled and annealed all the brass about 200 pieces, and now ready to start with a fully refreshed brass.
I understand that black soot = carbon build up is coming from some of the powders. But also can be a sizing on the old brass (I have no history how the other previous guy was sizing the neck or annealed at all)
My Question is....
The carbon build up is coming from over powered or faster powder? Or other way around low powered slow powder? Or what exactly makes a difference?
I cleaned thoroughly the barrel chamber and if possible I would like to avid any major polluting inside there.

Edit:
Asking because I am shopping for a powder and primers.
This what I would like to start playing with:
Lapua 308 Win brass, and Sierra 155gn Palma Match 2156
 
Last edited:
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Thanks All.
Suggestion?
Look for a higher power powder?
What I remember seeing the "old amo" powder was filled all the way to the neck, a friend reloaded me first time 46.6gn and second time 42.7 gn.
Not sure if more can be added next time when I will do it myself - unless crushing the powder with the bullet?
 
You can burn a lot of components and wear out a barrel or two trying to figure out what works. You already have Lapua brass and Sierra 2156 bullet. Now go out and get some Varget and stuff 46.0 grains into a case with Federal 210M primers and go shot. If you can't find Varget, get some VV N140 and use the same powder charge.
 
The front slope on the pressure curve is too shallow to seal the neck against the chamber.
Could be lack of neck tension or no crimp, allowing the bullet to move and enlarge the combustion chamber before enough pressure has built up.
Could be too slow a powder.
Could be too weak a primer, allowing an uneven start to the powder burn, especially if a ball powder.
IMR4895, IMR4064, and Reloder 15 are also good.
 
Generally a sign of low pressure. Not necessarily cream puff loads, but the shot start pressure is too low to expand the neck enough to seal.

I have a .204 that smokes the necks at maximum book loads and stops .6 of a grain over the book. Nosler brass.
 
bigHUN said:
Over the summer I inherited some amount of hand reloaded amo with my new to me heavy 308 project gun.
Shoot all these amo for fun scoring and testing at mostly 200 and 300 meters with pretty decent results.
And in meantime collected my new tools so I can reload further diy. (I chose the LE Wilson die combo, so I can develop my own from a fresh start).
I noticed a carbon fouling - build up - on some of the now empty brass shells maybe 50-50%, on some more visible on some almost nothing. Unfortunately I didn't pay attention right that moment at the bench which shots were painting the brass the most.
Tumbled and annealed all the brass about 200 pieces, and now ready to start with a fully refreshed brass.
I understand that black soot = carbon build up is coming from some of the powders. But also can be a sizing on the old brass (I have no history how the other previous guy was sizing the neck or annealed at all)
My Question is....
The carbon build up is coming from over powered or faster powder? Or other way around low powered slow powder? Or what exactly makes a difference?
I cleaned thoroughly the barrel chamber and if possible I would like to avid any major polluting inside there.

Edit:
Asking because I am shopping for a powder and primers.
This what I would like to start playing with:
Lapua 308 Win brass, and Sierra 155gn Palma Match 2156
Click to expand...

Not enough pressure, or pressure building too slow (too slow burn rate)

solvent in the chamber

brass might need annealing (but this is less likely)
 
Well, if you are getting decent results, I would not change anything, In your case prep regime include a stage where you wipe of the neck/shoulder area with Hoppes (or whatever) to remove the soot. Then do your work with the resizing die. You will keep the die a lot cleaner.
 
if you really want the correct answer then call hogdon or speer and speak with the tech staff
really makes no difference other than the fact you have some soot on the case necks
 
maynard said:
You can burn a lot of components and wear out a barrel or two trying to figure out what works. You already have Lapua brass and Sierra 2156 bullet. Now go out and get some Varget and stuff 46.0 grains into a case with Federal 210M primers and go shot. If you can't find Varget, get some VV N140 and use the same powder charge.
Click to expand...
This.
 
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