What causes excessive soot on a carriage body?

[mikecr]

I'm keen to learn what causes excessive soot on a cartridge body.

Excess clearances or low pressure load.
The beginning clearance to mind is chamber end clearance.
High clearance here allows gas to slip around the case mouth, potentially past the neck and shoulder, as it can prevent neck sealing. Excess neck clearance and excess head spacing aggravates the condition, as does slow sealing caused by pressure that's simply too low.

 

[rwj]

Excess clearances or low pressure load.
The beginning clearance to mind is chamber end clearance.
High clearance here allows gas to slip around the case mouth, potentially past the neck and shoulder, as it can prevent neck sealing. Excess neck clearance and excess head spacing aggravates the condition, as does slow sealing caused by pressure that's simply too low.

It can also be aggravated by slow burning powders that don’t build pressure fast enough…

 

[drop_point]

Sounds like you've taken too much brass off when turning the neck. No seal, losing pressure, thus lower velocity.

 

[243winxb]

what causes excessive soot on a cartridge body.

Slow powder, light neck tension, OAL extra long, standard primer, long bullet jump to rifling, throat diameter oversize, suppressor back pressure.
Any or all of these.

 

[243winxb]

Factory ammo of different brands may leave some soot. This amount is not a problem. Bolt gun.

 

[6MMsteve]

try some N555 it is a great powder, and of the high energy 500 series for Vita

 

[RRoe]

I've never seen this before not on Lapua brass just on Peterson all 50 6br

 

[RRoe]

Savage model 12 benchrest 6br factory shooting in factory class UBR

 

[Benchrest Braxton]

Looking at your load, grt shows you are only producing 43,000 psi. pmax allowable is 63,800 so you may need to up the load to be sure the case seals.

i am running 61-62 grains of 565 in my buddies prc with 153's. granted it is throated, but still.....

if you are a reloader you need to get confident with doing your own pressure ladders. viht is notorious for giving very conservative data.

560 would be better suited for you but i'm sure you can get 565 to give you better results if you just run it up to a higher operating pressure.

 

[Sniperhandle]

Too light a load is what causes this.