Ever D, in England back then Shultze, Imperial Shultze and EC Number 3 powder would be the main choices. Smokeless Diamond, Empire or Amberite were also mentioned. They would have been around up until around 1960 then Eley Kynoch started using Neoflak powder in magnum and heavy loads. In the 70's it would have been Nobel 64. Nobel 82 would have been used in the 80's. All these are slower progressive powders. Lagopus.....