Manson Reamers Go Gauge 300, 7mm Remington Short Action Ultra Magnum

When possible, Manson Reamers Headspace Gauges are made to SAAMI specs. If only CIP lists a specific caliber, reamers and Headspace Gauges are made to those specs. Calibers not listed by SAAMI or CIP are made to the designer's or most common specifications. Headspace is the dimension between the surfaces within the chamber of a firearm that hold the cartridge when the action is closed. If the headspace dimension is too small, a cartridge won't chamber. If it's too large, the cartridge will not b