There are several different Browning 45-70s.
There is the B-78, the 1885 Highwall in standard tangless, the 1885 Highwall Hunter with the tang, the 1885 Highwall Sporter with a round barrel, and the 1885 Highwall BPCR with the 30 inch half round/half octagon.
The mounts vary some since the forward base is affected by the barrel contour.
I have one of the tangless 1885s with the Browning mounts offered back in the 1990s. I bought it with a Leupold 12X fixed scope mounted and I have never removed it. It is strictly a range rifle for me.
I have another set of the Browning mounts and they look just like those in the Burris catalogs back then. Lepold makes bases now but the rear base extends forward off the receiver ring.
These rifles are low velocity to say the least. There is a good chance you will have a major elevation issue especially if you use a scope with limited internal adjustments. To be able to correct the vertical I recommend the Burris Signature rings with the manufacture recommended bases. You may also need a set of the Burris eccentric shim spacers. If you don't know how to use them read a lot and get some help if you can figure it out.
The Highwall design is one of the strongest on the planet, stronger than any bolt rifle. These rifles are also made in 7mm Rem , Mag, 300 Win Mag, 300 H&H Mag, and 300 Win Short Mag and few other dumb short magnum.
