Lyman™ Ammo Checker Single Caliber 7mm Rem Mag - 7833013 Lyman’s multi-caliber Ammo Checkers have proven to be extremely popular with reloaders since their introduction last year. Ammo Checkers are gauges that verify the quality and consistency of both reloaded and factory ammo. They are machined from solid aluminum and cut with custom tooling to SAAMI minimum chamber tolerances. Just drop your cartridge into the gauge and if it fits, it will chamber in your gun. Each gauge is clearly marked for caliber and is anodized in a bright orange color so that they will be easy to spot on your reloading bench.