The 45-70 will do anything the 458 will do out to 50 yards.The Alaskan Guides use the guide gun 45-70s to recover a wounded Grizzly up to 1600 pounds.They shoot them in the snout.The 458 is more an elephant or hippo or water buffalo gun where there is longer range involved.
My new years resolution was , buy no more rifles.
Now that doesn't mean I can rebarrel.
Seems to me, I always wanted a 45-70, but the 458 is that and more. I reload so any 45-70 load fits the 458.
thinking of a heavy barreled bolt 458, maybe 22 inch barrel, laminated stock. I'd use it for deer and bigger, thoughts?
Sounds like you answered your own question. IMO I think its a cool idea. To me the 458 is the way to go. The 45-70 will be more than enough gun but doesnt have the "cool" factor that the 458 does. There is also the 458 Lott.
You can get a new Remington 798 with laminated stock in 458 for about $700...I have one and it is nice.You can load it down, but it is fun with full throttle loads too...I put Speer 400 gr. 45/70 slugs in mine....Such a cool gun!...I'm sure that penetration will not be an issue.
There is probably no animal - including elephant - that could not be taken with a properly loaded 45/70. Modern steel in our rifles and modern powders have made the 45/70 feasible in today's world. The big 5 in Africa have all been taken cleanly with the 45/70. They guy from Rifle magazine shot through 1 buffalo and into another - killing both with nothing more than a hot loaded 45/70. With Hardcast bullets at 2000 fps and you could brain an elephant and not worry. We know for certain that 500 grain soft lead slugs at 1300 fps shoot through 1 ton American Bison with ease.
In my opinion, there is not much a 45/70 cannot do... all from a round that was around since 1873 is cool enough for me.