Description
This Gauge is designed to make sure that your rifle's chamber is safe and in spec. Basically, this gauge is precision machined to the maxiumum specifications for 5.56 NATO.
With a clean rifle, one should not be able to close a bolt on this gauge. IF one can close the bolt, the chamber possibly has too much head space, and would be dangerous to fire.
While most AR-15 barrels are high quality and are correctly headspaced at the factory, this gauge helps confirm that. It also, can be used on older, worn rifles to ensure their chambers remain in spec!