Were they fired in a Henry rifle by chance?
A fellow just brought me one which does the same, but much more-so. Blew the head right off on couple cases. The ones I tried bulged noticeably.
Looks worse in real life than pics...
How does the bore look in the one you have? Can't really see any rifling in mine by looking through the barrel with a light. When I took pics with the macro setting on my phone and a light shining in the action, I can see but it's not pretty.![]()