Perhaps we should clarify...
Is this line of discussion only concerned with the strongest lever actions chambered for pistol cartridges? If so, the 50AE and 454 Casull might then be considered but rifle cartridges still pack more wallop. Even from a manufacturer of hot loaded ammo.
Here's as close a match as I could find. Same caliber, same manufacturers info (
www.CorBon.com) and same weight. Note as a handgun cartridge 250yd data is not listed for the 454. Not only does the 45-70 have more energy downrange but it doesn't stall out as quickly either. At the muzzle, it's not even a contest.
Ex:
454 Casull 360gr Flat Point Penetrator
Range 0 50 100 125 150 175 200 yards
Velocity 1500 1387 1286 1241 1200 1161 1126 fps
Energy 1800 1640 1323 1231 1150 1077 1014 ft/lb
Path -0.50 2.01 0.00 -2.93 -7.27 -13.12 -20.58 in
vs.
.45-70 Government 350gr Bonded-Core Soft Flat Point
Range 0 50 100 150 200 250 yards
Velocity 1800 1658 1526 1405 1296 1248 fps
Energy 2519 2137 1810 1534 1307 1125 ft/lb
Path -0.50 1.33 0.00 -5.07 -14.55 -29.55 in
If y'all are really serious about the truly most powerful levergun cartridge - you should start with a rifle cartridge, not a handgun cartridge trying to be a rifle. Just my thoughts on the subject.
Happy Trails,
Texican