The 45-70 started out life as a black powder cartridge and as such the rifles built at that time were considerably weaker and could not retain the chamber pressures associated with today's modern ammo and rifles. Then came along stronger rifles like the Marlin lever action rifles which are able to safely handle much higher chamber pressures than the old black powder rifles. Then you have rifles like the TC Encore and Ruger #1 which are able to handle even greater chamber pressures than the Marlin rifles.

So, as a result, there are basically three levels of modern factory ammunition available for the 45-70 shooter. Think of it like hand gun ammo. you have standard pressure, +P, and +P+.

Power level #1 is for old rifles like the trap door and only generates about 28,000 psi of maximum chamber pressure and is safe for all rifles chambered for the 45-70 in good usable condition.

Power level #2 is loaded to about 30,000 - 42,000 psi of maximum chamber pressure and is safe for modern Marlin and Winchester rifles as well as other modern reproduction rifles like Sharps.

Power level #3 is loaded to about 55,000 psi and is safe only in Ruger #1's and TC Encores.



The 450 Marlin is based on a belted H&H case and is basically loaded to power level 2 of the 45-70 since it is a Marlin cartridge designed for their lever action rifles.


AS far as which one to get.... The 45-70 hands down.