The Webley was a very rugged and powerful revolver. The military loadings were smokeless and some of them utilized a 265 grain projectile at 750 fps. They were rated superior to the .45 Long Colt during military testing. But by the definition it is a conversion, so it would not have proofed in anything except its original caliber.

Although I have owned it for over 30 years and have enjoyed shooting it with mild cast loads, I have fired military FMJ through it.

Gasp! you say!

the Webley smokeless military loading of a 265 gr projectile at 750 FPS produces 330 ft/lbs of muzzle energy and roughly the equivalent pressures of a standard 230 FMJ at 800-850 .45 acp loading which produces ~350 ft/lbs of muzzle energy.

This isn't the appropriate firearm for everybody.