John:

Your "picture" of the cartridge is pretty clear. I hope I do not start a war, here, but the .455 is not very powerful.

I have basically little/no experience with it but its ballistics are nothing to write home about. I do have experience with the standard .45 Colt loadings and many others killing stock in the corrals and with that experience can interpolate pretty well what to expect with the .455. Having said that, compared to some others that were common as opponents guns, like the 8mm Nambu and .32 ACP, the .455 stands tall!

What I can tell you is this; I can see no difference in killing effect/reaction to shot on goats and sheep in the 40-250 pound range at all regardless of whether the round being used is the .45 ACP or 9x19 {or the others listed below except for the magums with JHP's}, so I doubt a 265 @ 600-650 fps is going to demonstrate superiority in any way, shape or form. I have killed dozens and literally tons of animals including cattle with service pistols including the following calibers; .22 LR, 7.62x25, 9mm Mak, 9x19, .38 Special, .357 SIG and .45 ACP, A few with the .45 Colt {w/ 265 grain semi-pointed Lyman 454190 bullet}, .44 Special, .44 Magnum, .357 Magnum and .41 Magnum. Some chickens with the .32 ACP...they were nearly bullet proof!

Anyway, NONE of the common service pistol calibers {including the .45 ACP} generate much for energy or severe traumaitc effect and I CAN say with certainty a slow moving 265 grain bullet is an unimpressive performer compared to a fast-moving 250 or so grain bullet.

Lethal? Of course, but in solid lead or FMJ persuasion {which is what military service calibers are stuck with}, none of them are much.

I had an Aussie FTR'd S&W M&P in .38/200 and for an anemic round, there it is. That one you mentioned, too, and in my opinion whoever authorized that thing for active service should have been court-martialled and married to an ankle chain for the rest of his natural life.