Roswell, I wonder how come they called it the '.44' Walker instead of the '.45' Walker? You ever heard anything about that?
.457...Seem's to me like that ought to be a .45...
Expressing the Caliber of a Barrel or cartridge wasn't standardized back then but the Walker is closer to correct than S&W's methods.
The Ball may be .457 when you get it but swaging it into the Charge Hole/ Chamber Mouth reduces the diameter to about .451, then when fired it enters a forcing cone which further reduces the ball diameter to about .449 which is the Bore Size of .44 plus the depths of the grooves.
The Bore size is the diameter of the bore as measured across the lands. When first bored out and before rifiling is cut the Bore is aproximately .44.
The S&W .44 is a measurement of the cartridge case or diameter of the Chamber, not the size of the bullet or of the bore either before or after rifling.
Thats why a .44 Magnum bullet measures only .429.
If the .44 Magnum had been a Colt Design it would have been listed as the .42 Magnum.
Near as I can tell the .357 is the only S&W Cartridge thats measured by the Bullet size.
The variations in method of identifying calibers exist in other cartridges as well.
The point .476 British Enfield Revolver Cartridge uses the same diameter bullet as the .455 Webley Cartridge. The .303 British projectile is actually larger at .311-312 than the higher numbered .308 which is measured by bore plus the grooves rather than by the bore alone.