I've tested the following in my Umarex Fusion .177:
Gamo Rocket 9.6 gr : 650 fps, 1.04" avg group (5 shot - 20 yds)
Crossman Premier Dome 10.6 gr: 625 fps, 1.18" avg group (5 shot - 20 yds)
RWS Diablo Basic 7.0 gr: 699 fps, 1.125" avg group (5 shot - 20 yds)
JSB Diablo Match 8.65 gr: 679...