To quote Massad Ayoob, "The 10mm's power exceeds that of the .357 Mag. and encroaches into .41 Mag. territory. Winchester's Silvertip line shows almost identical ballistics between the .41 Mag. and the 10mm: Each sends a 175 gr. bullet out of the muzzle at 1,250 to 1,275 fps."
and
"The big Glock 20 in this caliber was the backwoods choice of gun expert Chuck Karwan, who determined that with all 15 rounds in its pre-ban magazine and a 16th in its firing chamber, it carried more potential foot-pounds of energy on board when fully loaded than any Magnum revolver."
This would inlcude the combined energy of the 6 rounds in a Ruger .454 Casull.
The G20 in neutered form holds 10 rounds of 10MM (and Silvertips are not the hottest round out there). A S&W 627-8 holds 8 rounds of .357.