450- i upgraded from a marlin lever to a #1. Ran the hornady 350's and 500's with 3031. Used hornady data and it worked well on water buff . Prefered the 350s as the recoil and muzzle flip with the 500's was savage. Had it magnaported and reduced the muzzle flip.
Used it as a back up gun with the 500's,until I obtained a 458.
Tried the 300HP and liked them on boars , donkeys brumbies but didnt like there performance on buff so stayed with the 350's.The 350s were more versatile.
I still use the 350's in my 458, on lighter game.
Sold the 45/70 which was a mistake. Cheers Mick