I'm developing a load for my 8x57 Mauser.
2nd load I tried (45gn Varget, CCI LR primer, norma case, 170gn Hornady RN) went into 1.5" at 100 and pressure signs were fine, but there was soot around the case head and bolt face. Primers look fine, not flat, cratered or pierced.
It's not something I've encountered before, what causes it and does it indicate a problem?
Thanks in Advance, James