The SB-200 was not only designed for 22 rifle small bore competitors, but also for varmint hunters and plinkers. It will easily hold 100 rounds in the down position for easy access during competition. Space in the center is available which can hold two full 50 round boxes. The SB-200 holds up to 250 rounds of: 22 Long Rifle, 22 Long or 17 Mach 2, 200 rounds of 22 Win. Mag. or 150 rounds of 17 HMR. Recently retooled and now fits 17 HMR. The amount each box holds depends on if your ammo came in a paper or plastic box originally.