You can't cheat physics, but I can tell you that I am a reloader and you can load that 45-70 with some awesome choices these days! But my fav load is still 405gr hardcast lead I load that for Marlin lever and less powder for the 1873 Springfield Trap Door. Just love it.
I'm playing with different loads for my 500 Magnum. I have the revolver and Thompson Center Encore Katahdin. Anything from 300gr to 500gr jacketed flat point with a load of 296 is impressive! I'm tempted to get some 700gr hardcast just for shits and giggles.
Id love to try my hand at reloading ....Just don't seem to have enough time in my day . Those 430's were loaded to 2200fps and they definitely do some damage. I think the 550's were around 1300 but they hit whatever target you're shooting at like a runaway semi. Neither one is a round I'd wanna take past 250 yards with any confidence. I had some 325 leverevo rounds and those seemed to be a little better for reaching out, but still nothing like a .30.
That rifle has convinced me to buy a revolver chambered the same. Looking to buy the BFR in .45-70 now. Should be a good pig gun.