I havesomewhat limited experience with one canister of Jim Shockey's Gold FFG powder in my Mustang. I found it to be pretty accurate and clean burning, but yielded low velocities. For example:

300 grain sabotted bullet.
100 grains volume of JSG FFG -1264 fps (5 shot average)
100 grains volume of Pyrodex RS - 1393 fps (5 shot average)
100 grains volume of T-7 FFG-1755 fps (5 shot average)

385 grain Great Plains bullet.
90 grains volume of JSG FFG - 1018 fps (5 shot average)
90 grains volume of Pyrodex RS - 1144 fps (5 shot average)