When the .410-bore shell was introduced in the U.S. circa 1914-15 they were also called 36-gauge and 12 mm.
These 2-inch .410-bore shells carried a shot load of 3/10 ounce of shot. The 2 1/2 inch .410-bore shells carried a 3/8 ounce shot load.
The 3-inch .410-bore shell with a 3/4 ounce load was introduced circa 1933 with the Winchester Model 42 pump shotgun. The next year the 2 1/2 inch .410-bore shell got bumped up to the 1/2 ounce payload we know today.
For a few years Western Cartridge Co. also offered a 2 1/8 inch .410-bore shell --
Also, U.S. Cartridge Co. offered an all brass 2-inch .410-bore shell carrying the 3/8 ounce load of the paper 2 1/2 inch .410-bore shells.