Brownells AR-15/M16 Magazine Feed Lip Gauge 223/5.56

Convenient "Go/No-Go" gauge lets you quickly and accurately check for correct feed lip gap. Helps ensure reliable feeding and prevent weapon failure caused by feed problems. Simply slip over the back of a suspect magazine and lightly press gauge between magazine feed lips. If the gauge passes through feed lips, either discard that magazine or use the Brownells Magazine Feed Lip Tool (available separately) to bring them back into specs and restore reliable feeds. If the gauge won't pass through the lips, the gap is too narrow and must be widened. Machined from 4140 chrome-moly steel heat hardened to Rc 50-55 for dimensional stability, plus resistance to wear and corrosion. Mfg: Brownells SPECS: 4140 chrome-moly heat treated steel, in-the-white. Rc 52-60. Go: .454" No-Go: .476". For use on standard .223/5.56mm magazines only.