I have not shot the 45-70 ammo, but I did shoot some leverevolution 30-30 ammo. My barrel was not impressed. Each barrel is an individual, and mine just didn't like it. I've seen reports from others that did however.
I would NOT shoot "1886" level ammo from your Contender!
According to T/C, it's "trapdoor loads" only in the Contender frame.