It is very likely that the real story is "inexpert" chamber length measuring.

Yes, the Remington Hammerless Model of 1894 had 2 5/8" chambers, as did the Model 1889 hammergun and AFAIK Hammerless Model of 1900

1901 Model 1889 hammergun hang tag specified 3 Drams DuPont Smokeless Powder and 1 1/4 oz. No. 8 shot (511 pellets) in 2 5/8” U.M.C. “Smokeless” shells

A 1907 DEO Trap 12g Remington Hammerless hang tag specifies 3 Drams (22 gr.) “Infallible” with 1 1/4 oz. No. 8 “Standard Chilled Shot” in a 2 5/8” UMC Nitro Club shell

A 1908 hang tag for a 12g Remington 1900 KE Hammerless states that the gun was targeted with 24 grains (3 1/4 Dr. Eq.) of “Infallible” in a 2 5/8 inch U.M.C. “Nitro Club” shell with 1 1/4 ounce of #8 chilled shot.

Chamber length was not marked unless non-standard

An 1894 C grade with Etoile damascus

[Linked Image from photos.smugmug.com]

An 1894 DEO

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And Remington made no distinction between Remington Steel, Ordnance Steel, or Damascus regarding the recommended loads; all "Guaranteed For Nitro Powder"

[Linked Image from photos.smugmug.com]

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