KnockOut has a 10gr hollowpoint slug in .177 which works just fine in my HW97k, which is a 14.5 FPE gun out of the box. The exit velocity is 7.5% lower then a slightly heavier Diablo Field Heavy - which points to the larger contact area/friction of the slug. This gun really likes the H&N 8.64 gr Field Target Trophy pellets, but they lose 26% of their velocity after 50 yds. Whereas the Diablo Field Heavy (10.3 gr) loses 20%, and the KnockOut slug only loses 15% - which shows the lower aerodynamic drag of the slug. The slug had higher exit velocity variance than either of the two pellets above, so will have increased vertical group spread as a result - but not that much for say 50yds. From 50 yds to 70 yds the H&N FTT will drop 5-6 inches, and at 120 yds the drop is around 4 ft. I haven't tried yet to see what kind of drop the slug will have at 120yds but that should be fun.