There was someone offering a thin ring that would fit the Webley shaved cylinders for all the chambers. This would allow you to use the 455 cartridge, but do not think it
worked-out and still not that satisfactory.

I have S&W Model 1915 Type 2 that I purchased many years ago, it was in 455 cal. As the 455 cartridges became more difficult to find and the prices went up, plus difficult
for me to reload, I had this revolver rechambered to 45 Colt. I tried many combinations of reloads (even black powder) and never found this to be an accurate revolver plus
I was not happy loading seven or eight grains of Unique to use in this "old" revolver.

While checking over the cylinder chambers, I noticed that the original 455 Webly throat was still there as only the rear of the chambers were enlarged. I cut down about thirty
45 Colt cartridge cases to the same length as the 45 ACP case, loaded them with a 255 gr lead bullets and six grains of Unique and started shooting much improved targets.

With my S&W revolver you can not use 45 auto rim nor half moon clips just the 45 Colt rim will fit