A modern break-action like the H&R? Yes, absolutely.

The 45-70? In modern ones do not exceed the lever gun loads.

Not because they will blow up, but because the pins used to hold the halves together will stretch over time using hot-as-it-gets loads.

Something about the 45-70 . . . . I shoot the 425 grain hunter's supply laser cast lead at 1400~ FPS in my guide gun. It could be taken to almost 1800FPS before reaching max. But you gotta look at the math . . or shoot a very stable steel silhouette at 200 yards.

I shot a full size torso silhouette, after looking at the math, sitting on a very stable base at 200 yards. It knocked the target and the stand over. 1400 FPS is plenty, unless you need to stop an M1 Abrams. Then 1500FPS might be needed.