I recently loaded about a thousand rounds of .30 carbine. I found that in general the brass is very thick and I had to adequately bell the case mouths before attempting to seat bullets. When sized, due to the brass thickness, it's pretty much an interference fit between bullet and case without proper belling. Then, the finished rounds will show some swelling where the bullet is. But they were all within specs dimension wise and shot just fine.I didn't crush any cases, but all of them required significant trimming to get to proper length. All my brass was military and much was headstamped in the early fifties.