UPDATE!
Not totally satisfied with the regulation of the 300 grain hand loaded ammo that came with my used (new to me and actually, like new) Beretta 45-70, so I took a variety of commercial 45-70 ammo to the range last Saturday. The Hornady 325 grain bullets at 2000 fps had zing, but did not group well.

Next was the Remington Green Box 405 grain JSP. A right and left twice around and we had a nice 4 shot, 2 inch group at 50 yards + it was level with the Bullseye and 4 inches to the right.

All at once the rifle was regulated! With a lateral sight adjustment, ready to hunt.

:):)

I have 100 cases of primed brass and 100 Remington 405 grain JSP bullets and plenty of VV N133 powder
ready to be turned into ammo. Plus plenty of serious NF, Barnes, and Punch .458 bullets for DG if needed.

Now the gun shoots as good as it looks: