Quote Originally Posted by andrew375 View Post
First slug your barrel to find the groove diameter. Cast bullets have to be at groove diameter or larger. Unfortunately Marlins, I've slugged over a dozen, seem to be made on the large side. This is why Marlin microgroove barrels got a bad rap for use with cast bullets. My .45-70 marlin was. 4592", obviously. 458" bullets were a disappointment. Instead I made a mould that cast out at. 461" and sized to. 460" and all was good. A couple of other owners took my advice to use bullets as cast, without sizing, and that worked out well too.
Certainly true. My micro groove 1894 357 shoots like a shotgun with .357 lead, but like a target gun with 358.