My two cents worth. A Deputy friend had a Webley in 455 and mentioned that he'd like to shoot it, but couldn't find any ammo. I checked and both Hornady and Fiocchi make 455 ammo, expensive as it is. While checking, I noticed that Graf and Sons had new Fiocchi 455 brass at a good price and ordered 100 along with a set of Lee 455 dies. I loaded the rounds with 250 grain cast 45 colt bullets over a mild charge of TrailBoss. I presented him with the ammo, which he later claimed a kill on a charging armadillo. I patted myself on the back for a job well done. Later he announced that no more of the rounds would fire, so I got the Webley to check it out. It dawnwd on me that the revolver may have been modified to shoot 45ACP with moon clips. I secured the loaded moon clip in my M325 and it dropped right in. I then fired 66 rounds in 11 loaded moon clips loaded with 225 cast bullets(45ACP) with no problem. I cleaned and returned the revolver with an explanation of what happened. He's not a fan of moon clips, so I guess I'll have to get 100 auto rim brass and load him some conventional ammo. The point is, at least in this Webley, the cylinder had been shaved enough that the firing pin would not reliably strike the 455 rounds with their thin rims. Also, If I ever find an unmodified 455 1st or 2nd model S&W I would grab it up and shoot 455 reloads. BTW, the 455 is the same length as the 45 GAP. History sometimes does repeat it self. Bob!!