Be aware that Hevi-shot is harder than most of TODAY'S barrel steels. So, if there's contact for whatever reason, count on some scoring in the worst possible orientation from a wall strength standpoint.

I'm not dissing Hevi-shot which is certainly impressive, and I know that there are wads that are supposed to contain it. However, I'd still avoid using it in any valuable, irreplacable barrel, except possibly one that's chrome lined (and I'd check hardnesses and think carefully about that).

Fred