I went to the range with a good friend to sight in his new Henry Bigboy .45 Colt lever action and all the shells had a flashback burnt powder stain on one side of the case that concerns me. I have little experience with the larger bore lower pressure calibers (I shoot 25/06 and 243) so I thought I would throw this out for feedback. I do not know the type of shells he bought but they were bought at a gun show and are in a Hunter orange box.
Just hoping to find out if this could be a flaw in the firearm or more likely an ammo issue.