In schuetzen we use a 20 or 30 to one tin and pure lead mixture. we mechanically force the bullet into the breech end of the rifling before inserting the charged case. Some guys actually muzzle-load their bullets and breech load the cases. NO patch is used, just the naked lubed bullet into the rifling. the 20 or 30 to one is plenty soft. I imagine you could load a diamond for a bullet since we are using patches anyway.