Quote
These guns were made for the then-new Olin Super-X cartridge, in 12 gauge a 1-3/8 ounce charge of copper plated #4 shot.

No. The early Super-X loads were only with "special chilled shot." The Super-X loads in 12- and 20-gauge put up in Western's 2 3/4-inch FIELD shell were introduced in 1922. In late 1922 they added the 16-gauge Super-X load put up in the 2 9/16-inch FIELD shell. By 1924 they added the .410-bore Super-X load and the 12-gauge 3-inch Super-X load put up in Western's high brass RECORD shell.

[Linked Image from i.imgur.com]

The Lubaloy shot Super-X loads, put up in the high brass RECORD shell were introduced in the February 1, 1929 price list.

[Linked Image from i.imgur.com]