The 12-gauge 2-inch Remington Shur Shot shells seem to be pretty common. They appear regularly in the Wards Auctions. This full box went for $104 in the auction just ended --
Shur Shot 2-inch 12-gauge.jpg
I've been aware of them most of my life as my Father had one in his box of assorted shotgun shells in his gun cabinet. His shell is #7 1/2 C. All of them I've seen are Kleanbore so they are after 1931. The load given on the top wad in the shell my Father had is 2 3/4 dram equiv., while the box on Wards is 2 1/2 dram equiv. and your shells James are 2 1/4 dram equiv. all with a 3/4 ounce payload.
One more thing I notice is your shells, James, have the DuPont logo making them after 1934, while the box from the Wards Auction doesn't have the DuPont logo.
Love that label from Abercrombie & Fitch on the case with the name and address of the original purchaser.