David, at 10 pumps with a 7.9gr pellet is 645 fps for the model 66. It's a starting point.
I found this. - https://www.gatewaytoairguns.org/GTA/index.php?topic=16671.066 PowerMaster (from the 90s, probably applies to the latest iteration, the "Recruit", also)3 pumps = 432 fps5 pumps = 528 fps10 pumps = 618 fpsIt doesn't list the pellet weight but it's better than nothing.Cheers,J~