Is it really impossible to shoot old fashioned patched roundballs in a modern muzzleloader?
Depends upon the rate of twist of the barrel.
1 turn in 66" is for patched round balls.
1 turn in 48" is for conventional lubed lead bullets
1 turn in 32" (or faster) is for saboted pistol bullets and the modern spendy-trendy ML specialty ammo (Shockwave, Powerbelt, Aerotip, Gee-Gaw Gottem, or whatever Marketing comes up with this year)
The longer the bullet, the higher rpm (and tighter twist) needed to keep it flying point first.
I think the prices charged for some of these modern muzzleloaders and their fodder is outrageous for what you are getting..... It's not like there's a spendy action to make, and the pressures involved are nowhere near the 50-60K PSI like a modern centerfire cartridge generates..... so why are these guns costing what a modern centerfire gun does, if not more?
.....and a 385 gr plain cast lead ML bullet made by Hornady is 15 bucks/20 ($.75/ea. at Cabela's. A 300 gr jacketed XTP
is 20 bucks..... for 50 ($.40/ea). Seems to me there is a bit more involve in making a jacketed HP than a simple cast lead semi-wadcutter..... and the "powerbelt" plated or pure lead bullets with the plastic tip and a sabot stuck on the bottom can be as much as $2 each