I`ve got a .17 AH Bullberry barrel on a Contender frame. I made my own fore arm for it as the gun seemed to lite with what I had. With 10.4 grns. of H-4227, a CCI 400 primer and a 19 grn. Calhoon bullet I get 3,600 fps. and it shoots 1/2 moa. Max. point blank range( + or - 2 1/2 in. ) is about 290 yrds. I see guy posting that their getting a fair amount more velosity than this, but, that`s very close to max. in mine. The Calhoon bullets are very accurate in mine, but they are not fur friendly on coon size game, for them I shoot 20 grn. Berger MEF bullets. This is my favorit summertime carry gun.