Black soot build up on case heads

milo-2

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Joined
May 1, 2011
Messages
1,045
Location
Gillette, Wy
IMO, you really need to clean your chamber if gas has been escaping. I use a bigger brush, 338, then cut a 1 1/4" circle of scotchbrite with some C4 on it, chuck your rod up in a drill and spin it, then wipe it out.
Do you have a borescope?
 

ShtrRdy

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Jan 14, 2012
Messages
2,845
Location
High Plains
Ok, that means you have gas coming back towards you, your necks and or shoulders are not sealing off. The sides of your cases shoot have some carbon on them too.
I would look into this right now.
I dunno about that. The primer is pretty flat already.
 

Jakeweb09

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Joined
Feb 8, 2020
Messages
234
Location
Enumclaw washington
Are you sure that is carbon from being fired. Is there something on the bolt face that is transferring to the brass when fired? From the looks of your case, I don’t see why there would be carbon on the case head.
This thought has crossed my mind. It’s a custom build with a Stiller action, and the whole thing was coated.
 

doggonner

Member
Joined
May 31, 2020
Messages
14
Location
cave city ky
this could be gas escaping around the primer high pressure...watch out when I get black on the case head I investigate to see if it went up the pocket wall and squeezed out between the pocket and the primer high pressure be safe..are the pockets tight or loose if loose throw the brass away and get new brass and back off the load..if it will not come off it's gas do you have erosion on the bolt face
 

7070yshot

Active Member
Joined
May 26, 2020
Messages
43
Location
Liberty Hill, TX
Anyone ever get it? And what causes it? I’ve been getting decent build up on some cases but not all. Tried multiple primers and same thing. It’s happening on a 7 Saum with ADG brass and reloader 26.
Yes, I get this for a couple of reasons. In no particular order

1 - poor quality brass
2 - primers seared too deep or slightly crushed when being seated - primer pockets need to be uniformed depth
3 - blow back from chamber being in poor condition of some kind.
 

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