When thinking about these long barrel, long chambered 20-gauge guns, from the days before progressive burning smokeless powder, remember they didn't use a load any heavier than our 20-gauge Skeet loads of today, 2 1/2 drams equiv. pushing 7/8 ounce of shot. Back in the first 22 years of the 20th Century, our North American ammunition companies offered 20-gauge shells in 2 1/2, 2 3/4, 2 7/8 and 3-inch lengths. The maximum load offered in the 2 1/2 inch shell was 2 1/4 drams of bulk smokeless powder or 18 grains of dense smokeless powder such as Ballistite or Infallible pushing 7/8 ounce of shot. The maximum load offered in the 2 3/4, 2 7/8 and 3-inch shells was 2 1/2 drams of bulk smokeless powder or 20 grains of Ballistite or Infallible pushing that same 7/8 ounce of shot. Their main advantage was more/better wadding.
In 1922, Western Cartridge Co. brought progressive burning smokeless powder to North American 20-gauge shotgunners with their Super-X 1 ounce load put up in their 2 3/4 inch FIELD shell. Other makers followed suit and put their 20-gauge, 1 ounce, progressive burning powder loads up in a 2 3/4 inch shell. Peters Cartridge Co. is the one company I've found that offered their 1 ounce High Velocity 20-gauge load in extra length cases --