".45 Cowboy Special"
http://www.cowboy45special.com/siteb...on-205x171.jpg
http://www.cowboy45special.com/
.895 Inches in length.
Sounds like it might fit fine and get along well in some of our erstwhile .455s...or, depending on one's Head Space as per Cylinder to Frame condition, anyway.
But, this is mostly academic, ( or maybe suitable to odd-ball ones like mine where the Cylinder was shaved a little, but, nothing else was changed ) since honest to goodness .455 Webley/Eley Brass is available from Graf & Sons, as per Roadranger's above mention.