SK Semi-Auto Rifle .22 LR Ammunition SK's Semi-Auto Rifle is designed to outperform, replace and eventually retire all other inferior semi-auto ammunition offerings currently crowding the market. It's built to deliver pinpoint accuracy while functioning flawlessly through any 10/22 style firearms, AR's, 597's, 64's, and more. 50 Ct Box Ballistic Data: Weight: 2.59 g/40 gr Test Barrel Length: 660 mm/26 in