[VadeRetro]

The Webley-Fosbery really was a Semi-Automatic revolver. It was a pull of the trigger causing the shot to be fired with the recoil turning the cylinder at the same time resetting the hammer.

In The Maltese Falcon, Sam Spade's partner, Miles Archer, gets blown down a hillside with a Webley Fosbery aimed by Bridgette O'Shaunessy. Spade, shown the big hog leg of a revolver found at the scene, says, "Webly Fosbury forty-five auto. They don't make 'em anymore."

I was wondering if that was a mistake or perhaps the Webley was chambered for the .45 ACP round. You've just answered my question. Neither. It wasn't .45 ACP, but it was a semi-auto and a revolver.

[Shooter 2.5]

Right, but we can excuse Spade for saying .45 when he could have said .455.

After all, he didn't say ACP or .451 which is the true diameter of my 45 Autos.

[AnAmericanMother]

Actually, quite a number of the old Webley .455s that GIs brought back from WWII were bored out to take .45 ACP rounds, held in place with half moon clips.

You actually have to be a little careful when shopping for a .455 Webley (assuming you would want such an ugly thing and want to go to the trouble of finding the ammo) that it hasn't been bored out.

Much of the .455 ammo still circulating is Berdan primed and can't be reloaded, but there's an outfit in the upper midwest that sells new brass turned down from .45 Long Colt. In addition to trimming the case, they grind down the rim until it's thin enough to fit. The cases have slightly thicker walls than the originals, which will mess up your loading data (start with mild loads!) but once you get that straightened out they are great.