In some of the late 1930s Remington Trap Gun literature they show their Parker SBT with a Jostam Hy-Gun pad and their Parker double trap with what appears to be a Silvers or Jostam Air-Cushon pad.
In the same booklet their Remington Model 31TC and Model 32TC are shown with the Hawkins pad. A good pad from back in the day for a pre-mounted Trap Gun was the D-W --
As for the repro Hawkins pad, it is the really large size with 15 openings, and takes a very large stock to work. Finding a NOS with 13 openings is often the better option.