Up thru my 1913-14 Remington Arms--Union Metallic Cartridge Co. catalogues the closest thing to a 12mm/.410-bore shot shell I find is ithe .44XL and the .44-40 Shot. I don't have anything for 1915 to 17. In the 1918-19 Remington Arms--Union Metallic Cartridge Co. catalogue this is the listing for little shells --
In the 1923 Remington Arms Co., Inc. catalogue No. 107, this is the listing --
Finaly in a circa 1926 Remington Arms Co., Inc. ammo catalogue, this is the .410-bore listing --
None of these give the amount of shot in the 12mm/.410-bore shells.
In my 1927 Western Cartridge Co. booklet on Super-X shells Capt. Askins discusses the new .410-bore Super-X 2 1/2 inch shell with the 3/8 ounce load being a big improvement over the old 3/10 ounce .410-bore load.
