The 3 1/2 inch Magnum-Ten was introduced in 1932. A Parker Bros. 10-gauge double made in the 1920s would, at best, have been made for the 2 7/8 inch, 1 5/8 ounce, Super-Ten load brought out in the mid-1920s. There were very few original Parker 3 1/2 inch Magnum-Tens built. I probably wouldn't have to take off my shoes to count them! Ithaca that championed the Magnum-Ten only made 887.