Has anybody else chronographed the 262 grain Fiocchi .455 ammo? I got out to the range this afternoon and ran part of a box through my MK VI. Recoil was very soft, and the ten round average velocity was 554 FPS. I knew the Fiocchi was probably lightly loaded for these old guns, but it was even slower than I expected. Of course every gun is different, and another Webley it might produce more velocity with the same ammo. Just to satisfy my curiosity, I bullet the bullet on a round of the Fiocchi ammo and found the bullet weighed 263.4 grains, was .454" in diameter, hollow based, and loaded with 4.3 grains of unknown flake type powder.
FWIW, after a couple cylinders of the Fiocchi, I did see a lot of what appeared to be burned/partially burned/unburned or whatever powder in the barrel. Leading was not a problem, but the cylinder throats had a black soot like residue that was not easily cleaned out.
All things considered, I think I'll continue to use the light reloads in ACP and Auto-rim brass that I've been using.