UMC pistol round with wad around primer

The attached picture of a .450 Revolver cartridge (what else !) made by UMC has a card wad around the primer pocket - probably to take up space. (It was common for manufacturers to seat bullets directly onto the blackpowder charge. The wad would raise the level of the blackpowder to the correct point for bullet seating. On UMC .450 rounds using smokeless powder a case cannelure was added to hold the bullet prior to crimping.)

This round has a smooth case and unmarked copper primer.

According to the UMC production ledger, UMC loaded the 450 from 1889 but that had a folded head. The solid head (shown here) was introduced in this caliber in 1893.

(1). Has anyone any documentary evidence as to when this wad was introduced and discontinued?
(2). Has anyone seen this on other calibers from this era?

The .55 Wesson shot shell comes to mind with a (rubber) gasket filling the same space.
Sorry not to be of more help.

Thanks Pete. IAA member Lou B. of Montana has just told me that the wad is also found in rounds headstamped REM-UMC 450 with the unmarked COPPER primer (he sent me photos). I can confirm that REM-UMC 450 rounds with the unmarked TIN/NKL primer do NOT have the wad.

Chris, I don’t know if it relates at all, but yesterday Gourd sent me a thing on “Recent Patenets” from the 19th Century - just one page - and the following is shown:

“4,780. Cartridges. H.S. Maxim and R.R. Symon, London. March 4th, 1893.
Relates to rifle cartridges charged with smokeless powder and consists in the application of a disc of nitrated cloth to the flash-hole of the cap chamber to prevent the too rapid ignition of the powder charge by the detonation of the fulminate. The disc is ignited by the cap and serves as a “primer” to ignite the charge.”

I assume the patent is a British one, because there is a U.S. patent shown right above it for some sort of wad with a number of 22,780.

Again, I have no idea if this relates to the “primer wad” in the .450 round. With the small powder charge, I don’t see how it would, but thought I had better relate it here, primarily due to the very coincidental date of 1893. Most of the details of this old revolver stuff baffle me.