Hi Bob,
The factory loads for a .45-70 are mild! That is unless you buy the hot stuff from Buffalo Bore or some of those guys. A 10" Contender is never going to be much fun to shoot in .45-70 unless you like muzzle blast and recoil. It is an old, old rifle cartridge and it has the capability to be loaded to have power to kill anything that creeps, crawls, or makes a racket. I love shooting pistols and Contenders, but I have to think you could find a better caliber for a 10" Contender than a .45-70. Just my 2 cents!(from a gripy old man)
BT