The 2 7/8 inch 1 5/8 ounce load is the Super-Ten. It came out in the mid-1920s and was a BIG jump from the heaviest previously offered factory 10-gauge loads of 1 1/4 ounce. The 3 1/2 inch case with a 2 or more ounce load is the Magnum-Ten. It was introduced circa 1932 with the beefed up Ithaca NID to handle it. That seems to have been the first use of term "Magnum" in American shotshells. Then about 1935 Winchester/Western upped the payload of the 3-inch 12-gauge Super-Speed/Super-X shell to 1 5/8 ounce and called it the 3-inch magnum.
