Hornady still makes a lead "cowboy" bullet sized to .454 inch, which works well in this caliber. Hornady Manufacturing Company :: Search results

Here's some information / experience I have gleaned over the years with this round. I hope it's not way more than you want!

1960s vintage Lyman Manuals have loading data for both the longer Mk I and the shorter Mk II cartridges.
Old manuals are usually available at gun shows if you look for them.
Also, Pet Loads by Ken Waters has a lot of very useful information and load data on the .455 Eley/Colt/Webley.

By the way, if you are interested in the history of this cartridge "family", Cartridges of the World is a good place to start.

My understanding is that the .455 Eley, the .455 Revolver Mk I, and the .455 Colt are all basically the same cartridge. The case length is 0.880".

Originally a black powder round, ".455 Revolver Mark I" was the British Army's designation for the cartridge when they adopted it in 1892. Perhaps Eley wanted to put their own name on the round for commercial sales to civilians? (Colt always hated to put anybody else's name on their barrels, so they had to “create” a round and name it after themselves ).

When smokeless powder was introduced, the British Army went to the shorter, more efficient Mk II version, with a case length of somewhere around 0.770", depending on the reference you are looking at. Colt continued to make the longer round, using smokeless powder of course, up until around WWII or shortly thereafter.

Buffalo Arms has both cases (you need to go to their website for up-to-date information and prices). The .455 Colt is $38/100 and the .455 Webley Mk II is $25/100. When I bought mine a few years ago, they were made from .45 Colt brass cut down to 0.890" and with the rim properly thinned.


I would advise against buying the Fiocchi rounds if your intention is to save the brass and reload it.

A few years back, I bought some Fiocchi .455 Mk II ammunition and shot it in my New Service. Several of the cases split on their initial firing (ie, factory fresh, not reloaded). On examination, I could see that the case walls are really, really thin.

I only had this case splitting problem with ammo from one box; the rounds from another box did not split. Still, I would never reload this thin-walled Fiocchi brass.

One other oddity - Fiocchi uses small pistol primers for this round. I don't know how much an issue this is, but it seems odd for such a large diameter cartridge to use small primers. In any event, the reloading data I have seen calls for large pistol primers.

“Will the longer MK I cases chamber in S&W's chambered for .455 Webley? “
There is an easy way to find out.

If you don't have a fired .455 Mk I case, get a fired .45 ACP case and insert it to test for chamber length. If it goes in flush with the back of the cylinder, or nearly so, then the .455 Webley Mk I will also fit since its case length is the same.

Of course, just because a round will chamber does not mean it is safe to fire it in that particular revolver. Remember that many British revolvers were made during the black powder era and it is not safe to shoot smokeless rounds in them.

Also, some revolvers were converted to accept .45 ACP when they were imported to the US. These conversions were done to increase sales, often with little or no regard for safety.

It may be wise to do a thorough investigation, including advice from a knowledgeable gunsmith, before shooting one of these old revolvers.

I bought several boxes of loaded Dominion .455 Colt from a local gun shop. They said they got it from another little shop that went out of business. It pays to keep your eyes open.
[Shown below with Fiocchi Mk II for comparison. Note the small pistol primers on the Fiocchi rounds.]

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