I've been thinking of getting a 45-70 and was recently looking at load data for the cartridge. In doing so, I come across load data for the 50-140. I was amazed with the velocities the loads yielded in heavy conicals, e.g. 1945 ft/sec for 515 grain conical. 
It did this while generating pressures less than 24,000 psi.
The loads used Varget, 4831, and 4350.
For me, thats way to much power (and recoil) at 4286 ft. lbs M.E. But it did occur to me that these Savage owners may be missing out on something. These powders operate well at even lower pressures and after some make shift calculations, I fudged the possibility of velocities of 1700 ft/sec for the Great Plains 460 grain conical at pressures in the 15000 to 16000 psi range. Now thats a ME of 2950 ft lbs and energy above 1950 ft lbs at 150 yards with a +- 2.5" trajectory.
Granted, these powders are of little use with the light saboted bullets Savage owners are using, but then we are not dealing with operating pressures of 44,000 psi of their recommended sabot loads either.
Is it that these slower burning powders are more difficult to ignite with the 209 primer?
Whatever the case may be. I think I'd rather shoot a 460 grain conical with my BP rifle than any saboted round from the Savage. Sure it will require little more hunt preparation and getting closer to game. But to me, "That is what hunting with a muzzleloader is all about".
Phil
It did this while generating pressures less than 24,000 psi. The loads used Varget, 4831, and 4350.For me, thats way to much power (and recoil) at 4286 ft. lbs M.E.
But it did occur to me that these Savage owners may be missing out on something. These powders operate well at even lower pressures and after some make shift calculations, I fudged the possibility of velocities of 1700 ft/sec for the Great Plains 460 grain conical at pressures in the 15000 to 16000 psi range. Now thats a ME of 2950 ft lbs and energy above 1950 ft lbs at 150 yards with a +- 2.5" trajectory. Granted, these powders are of little use with the light saboted bullets Savage owners are using, but then we are not dealing with operating pressures of 44,000 psi of their recommended sabot loads either.
Is it that these slower burning powders are more difficult to ignite with the 209 primer?
Whatever the case may be. I think I'd rather shoot a 460 grain conical with my BP rifle than any saboted round from the Savage. Sure it will require little more hunt preparation and getting closer to game. But to me, "That is what hunting with a muzzleloader is all about".
Phil