Traditional 45-70 loads are adequate for deer and black bear but are underpowered for larger game. 45-70 was never a commonly used round for bison. It wasn't potent enough to kill them reliably for one thing, and most of the bison were dead before it was introduced.
There's a lot of dead "larger game" that would argue with this, if they could. .45-70 has been used for bison and other game since its introduction in 1873. It is ABSOLUTELY potent enough to kill them reliably.
The MARKET hunting slaughter of the bison herds was winding down and essentially ended shortly after the .45-70 was introduced, so few of them made it to the hands of the market hunters, who already had rifles that worked and weren't terribly interested in replacing them at the time...
The ARMY shot buffalo, cattle, horses, people and every thing else they shot with the .45-70 and had NO issues with its "potency" if anything, they REDUCED some of the original loads, over time.
Everybody spouts the same bs about being able to reach 80% of 458 Win Mag energy with a hot 45-70, but nobody wants to try.
ITs NOT BS, Scorch, some of us have done it. And yes, the recoil is up there, there's no free lunch. Just because we don't regularly shoot the really heavy loads for plinking and recreation doesn't mean its BS. I have a .458Win Mag, too, but I don't shoot 500gr elephant loads from it for fun, either. I COULD, but I choose not to, for both my own comfort, enjoyment, and the savings on my wallet.
The speedometer in my car goes to 140, (probably overly optimistic) I've had it to over 100...the fact that I almost never drive it that fast, that most of my driving is done at 80 or slower doesn't make the fact that it can do 100 BS. Not in the least.
The T/C CONTENDER is stronger than the trap door Springfield, but not quite as strong as the 1886 Win lever gun or the modern Marlin. Top loads for those rifles are just a bit too much for the Contender. I run mine at Trapdoor load levels or just slightly over with no trouble.
I do not know what strength level a T/C ENCORE .45-70 would be grouped in, but I wouldn't put it in the same group as my Ruger No.3.