In response to DannyD (I can't seem to getthe quote thing to work) It should be safe in your new gun. I think he was referring to older models that might not take the pressure. I think it's really more of an issue in the 45-70. Marlin rifles built before the '70s tend to be a bit weaker than the new ones. The big issue with the 45-70 is that was originally a black powder military cartridge in the sharps and Spencers, and later in the 1886 Winchesters, and 1895 Marlins. Those rifles absolutely will not handle the pressure of full house modern loads.