I have a 32 Cherokee barrel that I am thinking of having re-bored to a 40 cal. recommendations on rifling type, deep or shallow and rate of twist. Its a 24 inch barrel and would be a PRB gun for punching paper. Also how hard would it be to have the 32 removed from outer barrel and re-stamped 40. Its a good barrel but want a 40 and this may be a cheap way to do it with a platform that I really enjoy shooting.