At the time Tobin doubles were introduced, 1904, smokeless shotgun powders had been in existence for something like 28 years. Factory loaded smokeless powder shotgun shells began being offered by UMC in 1891. Winchester followed by supplying them to "selected shooters" in 1893 and to the general public in 1894. When the Tobin double was introduced in 1904, the heaviest 12-gauge loads being offered by our North American ammunition companies were 1 1/4 ounces of shot pushed by 3 1/2 drams of bulk smokeless powder or 28-grains of dense smokeless powders such as Infallible or Ballistite. Sure there were many lighter loads being offered, but we all know the North American Nimrods penchant for "more is better" so these guns have seen their share of heavy loads over the last 100 plus years. According to some DuPont shotgun powder booklets in my collection these heavy loads developed 11,700 to 12,600 pounds, above SAAMI specs of today.
By 1922 we were getting shotgun shells loaded with progressive burning powders, Western Cartridge Co.'s Super-X loads leading the way. These brought us higher velocities and in the smaller gauges heavier payloads, all at actually lower pressures. By 1925, we got the 12-gauge 3-inch Super-X load with 1 3/8 ounce of shot. In his 1930 catalogue G.B. Crandall was offering his D-Grade Tobin made for these 3-inch high velocity loads.
