Apologies for raking up an; ‘old chestnut.’
Some of the earlier confusion (on my part), in the ID for the Eley .577 Snider (1 -5/8"), might have arisen from an item in Eley Cartridges by C.W.Harding. As mentioned earlier, my example had ‘Howdah’ written in felt-tip-pen, on the side, by the previous owner.
The headstamp of my example is listed in; ‘Eley Cartridges,’ as .577 Revolver.
Also, it is mentioned that the .577 Howdah has the same length (1.61" approx. 1 -5/8") as the; ‘Eley Snider,’ you showed, from the 1893 Catalog.
Have only just purchased the book, consequently; it’s a very new viewpoint for me.
I’ve still, not quite, got over the price of the book!
My belief, is that the Catalog entry you provided, is the correct description.
I also have a 2" solid case .577 Snider with a headstamp: Kynoch .577.S
Is it possible that the Eley .577 Snider (1 -5/8") could also have been an ‘option’ for the Howdah?