While the 2 5/8 inch 12-gauge shell was "standard" in the U.S. from the beginning, when Winchester introduced their Model 1897, it was made for 2 3/4 inch shells. Likewise the Remington Autoloading Shotgun (later Model 11), introduced in 1905 and the Remington Repeating Shotgun (later Model 10), introduced in 1908, were made for 2 3/4 inch 12-gauge shells. In the late 1890s to at least 1905, the U.S. amminition companies were offering smokeless powder loads as heavy as 3 1/4 drams of bulk smokeless powder pushing 1 1/4 ounce of shot in 12-gauge 2 5/8 inch paper shells. By 1910, they had backed off, and the heaviest 2 5/8 inch loads offered were 1 1/8 ounce of shot. From then on one had to go to the 2 3/4 inch or longer shells for 1 1/4 ounce loads.
For some time I was under the impression that the extra length paper shotshells came in with the increasing use of smokeless powders in the 1890s, but recently I found this in the 1880 UMC catalogue --
It is a bit hard to read, but 12-gauge 2 5/8 inch paper shells are $10.50 per thousand, and 12-gauge paper shells up to 3 1/4 inch are $12.00 per thousand.
