Yeah - bolt guns are definitely different from doubles. I shot 34 grouse one fall with the .458, some simply changing the full power load (when time) for one loaded with 15gr. AL8, case full of kapok and a 230gr. Speer swaged 230gr. They shot to the post in the scope reticle at 25 yards, so easy to shoot their heads off.
Velocity was 1,350fps & would shoot into 3" at 100 meters.