Size Isn't Everything - British Cartridges:

 Come on Guys - we're talking 'man stuff' about shooting - not ...

Cartridge designation is an absolute nightmare of a mess that means we need to be very careful - because using a wrong round can cause a dangerous KABOOM - even using the right round in an older gun can be disasterous if that round is loaded to a later more powerful specification than the early firearm was built to use .. such as a smokeless powder load rather than a black powder load.

The particular rounds I want to consider seem, from the names, to be very different cartridges ..

The .450" Adams aka .450 Boxer Mk I can also be called: .450 Revolver, .450 Colt, .450 Short, .450 Corto, .450 Mk III, and .45 Webley. 

The .455 Webley naturally is also known as .455 Eley , and .455 Colt. (various Mks.)

The .476 Enfield is also known as .476 Eley, .476 Revolver, and .455/476 (a clue)

Three different sized Calibers right? ... Well NO, - wrong actually as they all three use a .455 inch diameter bullet - unless you accept that the .455" offically used a .454" pill (maybe).

The ".476" refers to the brass CASE Diameter - not the bullet - and each of these designations of rounds are detailing small changes in specification upgrading performance while leaving the earlier cartridges still useable in the revolver. There are changes to the cartridge case length and capacity.

These are proactive changes - NOT retroactive. - Be very cautious in what you might be tempted to fire in the earlier model firearms.

Note: The rimless .45 ACP or 45 Colt is meant to use bullets that measure .452 inch.

These calibers have such long histories that there are developments and changes with time - with cross-use, plus there is a small degree of flexibility in the actual size of projectile that can be used - resulting from commercial manufacturing tolerance and the fact that lead (copper too but less so) is to some extent malleable and 'plastic' and is intended to fit itself to the bore of a firearm in a gas sealing manner - by expanding under pressure and obturating.

This is a link worth taking a look ..

https://forum.cartridgecollectors.org/t/476-enfield-revolver/30418

- Could someone use bullets made for a 45 ACP to reload for a .455" Webley? - That would depend ... many war surplus Webley .455 revolvers were cheaply modified to accept .45 ACP ammunition and sold,- some have not yet blown-up.

Marty K.