I obtained an original Parker Hale 22RF conversion kit for my 455 Webley. The kit was for the 6" barreled Webleys and was composed of an insert barrel using a a knurled sleeve at the muzzle to tighten and center the 22 barrel in the 455 barrel and a complete replacement cylinder holding six 22 rimfire cartridges. The normal firing pin worked on the 22 cartridges. As my Webley was a 4" barrel model I made up an adapter that was used in place of the sleeve to accommodate the 2" of 22 barrel extending from the muzzle. The adapter locked and centered the insert barrel and looked just like a silencer.

The '22 Webley' was just as accurate as the parent cartridge and the Webley functioned the same as the 455.

Sold my 22 conversion to an owner of a 6" Webley, I could cast and shoot the 455 just as cheap as shooting 22 Rimfires and it was more fun with the bigger cartridge. Recall shooting a few bunnies and possums with the 22 Webley before I sold it on but shot many more with the big Webley in 455 guise.