Precision headspace inspection tool for .300 AAC Blackout rifle cases. Simply insert your case to verify it stays within safe minimum and maximum dimensions. Identifies cases exceeding maximum length or headspace limits.
Proper headspace is fundamental to safe, accurate reloading. This Lyman gauge allows you to inspect your rifle cases after resizing to ensure they meet critical dimensional specifications.
The gauge operates on a simple principle: insert your resized case and verify it falls within the safe zone. The tool identifies cases that exceed maximum headspace or case length limits, protecting you from potentially dangerous ammunition.
Headspace—the distance from the bolt face to the chamber's datum line—directly affects safety and accuracy. Cases with excessive headspace can cause dangerous pressure spikes or premature case failure. Cases below minimum headspace may not chamber properly. This gauge takes the guesswork out of quality control.
Any case found with excessive headspace should be destroyed immediately. Do not attempt to reload or reuse it.
Whether you're a precision rifle competitor or a careful handloader, this Lyman gauge is an essential addition to your reloading bench.