MTM SB 22 Ammo Box The favorite among 22 rifle calibre small bore competitors. There is enough reserved space for boxed ammo or loose rounds. Features a Snap-lok latch and a fold down handle for easy transporting. Retooled in 2008 and now fits 17 HMR. Please see the MTM Pistol & Short Rifle Ammo Chart download below to check which size you require.