Lyman MSR Ammo Checkers are machined from solid blocks of aluminum and cut with custom tooling to minimum chamber dimensions. Check the quality and consistency of both loaded rounds and purchased ammo. Covers 223/5.56, 6.5 Grendel, 6.8 Rem. SPC, 7.62×39, 300AAC Blackout, 450 Bushmaster, 458 SOCOM and 50 Beowulf.