The .458 Lott is a stretched .458 Win Mag. Lott stretched the case so he could get enough powder in it to actually achieve the original claimed .458 Win Mag ballisitics.
The Ruger in these calibers feels
heavy. I have a No.1 in .375H&H and I swear it
feels twice as heavy as my No.3 in .45-70! Thats because all the weight seems to sit in that thick, heavy barrel.
Probabaly not the best choice for a dangerous game rifle, (only because its a single shot),but far from the worst. As to the reload under stress, that's you, not the rifle.
The beauty of this rifle (and getting it at a good price really adds to the appeal
) is that by handloading, you now have a rifle good to take anything that walks on earth. You can shoot .458 Win Mag brass in it (save the Lott brass for when you really need it), and you can load cast bullets at any speed you like up to full bore.
A load matching the black powder ballistics of the .45-70 will have a fairly light felt recoil in that heavy No.1, and take everything in North America, if you can get within the range that you can make a good shot. 400gr cast loaded in the 1800fps range extends that distance some. And you still have plenty of "throttle" capacity left.
And the big bore rifles are generally still very accurate with reduced loads.
One word of caution, when handloading with jacketed bullets, make sure you choose a bullet that is right for the target, AND right for the speed you shoot it. IF you push a bullet designed to expand at .45-70 speeds all the way to 2000+fps, it will act like a varmint bullet. Explosive expansion (with matching change in penetration. Have seen deer hit with a load like that, and while the job was done (deer was anchored, decisively) only about half the bullet was still in one piece and a pretty fair amount of tissue was really "messed up". A hard cast slug or a heavier jacketed one, at the same speed would have left a clean hole and still gotten the job done just as well.