When Slavko is preparing for the final confrontation, he checks that his revolver is loaded and we see six previously fired shells (as indicated by the dented primers).
When Montana enters the warehouse, you can see that the rifle's safety switch is set to "S" - meaning he would be unable to fire the weapon.
When Montana is first rescued by Dimitrije, he has a large knife wound on his left arm, which Dimitrije stitches up for him. Shortly after in the steam room scene, the wound has completely disappeared.