The little 2 1/2 inch Lyalvale Express 3/4 ounce 20-gauge load may be one of the finest 20-gauge loads for use in old doubles ever. Wish I could still get them here in the U.S. Same with their 2 1/2 inch 7/8 ounce 16s of which I still have two boxes. Lite RSTs are a close second. The Eleys and Gamebores have always seemed very harsh to me.
I'm sure that if a 1919-vintage 20-gauge L.C. Smith was living here in the U.S. that North American Nimrods would have been stuffing one ounce Super-X type 2 3/4 inch shells in it from their first appearance in 1922, and likely some of the 2 3/4 inch 1 1/8 ounce magnums after they appeared in the 1950s or 60s. I'm equally sure that the L.C. Smith bolting and barrels stood up to it just fine. On the other hand the delicate head of the L.C. Smith stock no doubt suffered greatly. It seems no one here paid any attention to the short chambers in these old doubles until the late 1980s or early 90s.