The .450Marlin is the modern arm shooter-but non-reloader's version of the .45-70...i.e., if you're shooting a modern arm, like my favorite, the Marlin 1895's, the .45-70 can actually surpass the .450 in power for a handloader, while typical factory .45-70 rounds are loaded to fairly low levels in deference to old trapdoor's and rolling blocks that weren't made to withstand the pressures that modern day firearms are capable of...a non-handloader either has to pay premium prices for Garret or buffalo bore "high power" .45-70 rounds, or buy a .450M.

I'm a .45-70 shooter, always will be, I've had a .450M to try one on, but I wasn't impressed by it-like I said, a reloader can get superior performance from the .45-70...here's the skinny, Non-reloaders: get the .450 because "standard" factory rounds give the same performance as the "premium" .45-70rounds.....Reloaders: the .45-70 can be pushed well beyond the .450M (especially with heavier bullets), and .45-70 brass can be had much cheaper than .450M's-which will likely remain true indefinately, although the gap will lessen as the .450M becomes more common.