Have a 1893 Marlin in 38-55, went out to the range on Wednesday and put 10 rounds through the old girl made in 1902. I was using WW brass and the primer hits were round and very flat and deep covering 2/3 of the primer face, I chocked this up to the Winchester thick brass. Went out to-day with the same load combo using Star Line brass figuring that would solve the issue, no such luck primers look the same. A .379 cast bullet just hardly starts in the fired Star Line case, have a couple bullets cast to .378 and they won't even begin to enter the WW case but will start in the Star Line brass. The primer hit really bothers me as i have never seen a primer hit that way. What do you all think is happening here, have never slugged a chamber before?