As the .17 Furball

is an almost identical twin to the 17 Mach IV you owe it to yourself to get some Benchmark and some 25 gr bullets (Berger HP's were originaly specified, but with the Fireball's 9 twist, the V-Max may work well). Somewhere around 18.4-18.8gr should give you them bug-hole groups everyone LUVZ.
Gotta LUV the Mach IV or its more contemporary cousin
Bob