A barrelmaker named Bellm says you don't need .357 max brass in a single shot. Since a .357 mag runs at the same pressure as a Max, you load a .357 mag case to .357 max specs and seat the bullet out to .357 Max COL.
The crimp groove will be halfway up the barrel, which would be a disaster in a revolver, but not in a Martini or Contender.
