I have Ruger #1's in both .375H&H and .458WM. The .458 has a faster rate of twist (from what I hear) than the #1's in .45-70 AND having that faster rate of twist do better with the 500gr and other heavy boolets. My point: research the rate of twist for the range of boolets you're going to shoot.

Why not do a switch-barrel and keep both calibers? The heavy .375's have some advantages at longer ranges. Both hurt your shoulder about the same (max loads).

The switch barrel idea sounds interesting. I used to own several when I was into bench rest shooting.
Wonder how accurately the iron sites would index? Never worried about that with the bench guns, as the scopes were receiver mounted.

Just a bit more info. My favorite bullet in .45 cal. rifle is the old Lyman #462560, a G.C. bullet Lyman cites as casting 545 grains, but mine never came quite up to that.
It has a real "hammerhead" shape and is devestating on both ends.


Would want the twist to stabilize from this weight and configuration down to the 405 Grain R.C.B.S. cast bullets.

It isn't too difficult to hit the 2" o.j. bottle lids at 90 yards with iron sights with the .458, so who needs a scope?