VERY VERY moderate .45-70 load.

The Hornady LeveRevolution loads are running pretty conservatively, and in my 18.5" Marlin Guide Gun 1895, the 325grn FTX runs 1795fps.

That means a muzzle energy of 2325ft.lbs.

I push 90grn pills from a .243win to 3200fps, that's about 2045ft.lbs.

That's 15% more potential energy.

Now compare the increased bullet diameter component and the overall momentum value, i.e., the Taylor KO factor...

.45-70 .458", 325grns at 1795fps = 38

.243win .243" 90grns at 3200fps = 10

What's that mean? For equal penetration depth, the .45-70 will do about twice as much damage, for equal expansion, it will penetrate about twice as far (energy shed is an exponential function, 4x taylor equates to about 2x relative factor, i.e. 2^2).

So nice try, but you missed the boat...