Does it look like this?
This one is also a 1917 date
The "shaved" Webleys are much more common than uncut ones these days, because when the supply of .455 ammo dried up it was a way to keep the gun functional.
Many people have shot these converted guns for decades without trouble, and so believe that it is fine. Some have had their guns come apart, and know its not fine.
Essentially standard GI .45acp ball ammo is proof level load for the Webley MK VI. Each and every round is the equal to a proof load, and while some guns can handle this some eventually fail. DON"T do it. AND, REALLY DON"T shoot anything hotter.
The Webley is physically a big gun, which makes people think it is stronger than it actually is. Its fine to shoot a converted Webley with .45ACP BRASS, loaded to a level the Webley can handle. Its not fine to shoot .45ACP AMMO.
The Webley is built for a 260gr bullet moving at a 600-700 fps speed.
Note that some Webleys that were shaved will handle the .45Auto Rim brass as well as ACP brass in half moon clips. Some will only handle ACP brass in clips, and the AR brass's thick rim will drag on the recoil shield, possibly to the point where the cylinder won't rotate. Look at the rear edge of the cylinder. If just the bottom edge of the numbers is shaved off, AR (auto rim) brass might not work. If a larger portion of the numbers are missing, AR brass might work acceptably.
Best practice, DO NOT SHOOT YOUR WEBLEY WITH FACTORY .45 ACP AMMO!
Shoot your Webley with proper handloads in .45acp cases with clips.