I was talking with a fella in Washington state that makes case inserts on a lathe for cat sneeze loads in a 45/70. He glues them in with Locktite so they can be removed with heat when the case life is over and installed into fresh brass. He PMed me a drawing and a photo.
Started working on a 375-06 imp with a 1-8 twist. TrailBoss is working out real well with a 350 gr. bullet. With the rifeling being stripped - is the bullet being over sized, hardness, gas checked? Have had to go with a softer bullet for it to "slug up", and the gc will definately help.