Nice video by LifeSizePotato's channel, drawn from his eclectic gun collection. It's a quick way to determine if your Webley's cylinder has been cut down and modified for .45 auto and moon clips in place of the rather harder to get (in the states) .455 Webley. A lot of the guns here have been modified, but most Webleys really aren't strong enough to plow away on off the shelf 230 grain 45's. The one's built since 1915 can take it in my opinion, as their cylinders were beefed up for nitro powder and are pretty strong.
Has your Webley been cut?