I see your point on the 'other' ammo, bigboar. When I had my .458 Alaskan which easily duplicated 1960's factory .458 Win. Mag. loads, I chose to load it down for NA game. What I picked was a good shooting load of Reloader #7 powder and the 400gr. Barnes Spitzers, at 2,150fps. The recoil was a little more than the same ballistics from the .458 2", however was considerably less than 500gr. bullets at the same speed.

I used it primarily as an in-camp grizzly protection for the cook and her kids. I was physically unable to guide at that time, but could sit in camp, eat her baking, drinking coffee and doing guard duty. Yes - it was boring, no grizzlies every showed up while I was there, but the "job" was done & I am sure the load was up to the job at hand.

I cannot imagine having to shoot factory ammo in a .458 Winnie or the Lott for that matter. If I wanted to shoot any gun well enough to become proficient with it, handloading was necessary, for me.