Instant, At-A-Glance Barrel Throat Wear Indicator
Gives accurate, comparative readings on actual barrel throat
erosion for all M1, M14 and M1A .30-06 and 7.62mm Nato, High
Power Service Rifles. Insert in empty chamber and take reading
every 1,000 rounds to accurately measure and track barrel throat
erosion.
Big Book Catalog, Issue:65, Page:482
Law Enforcement / Police Store, Issue:02, Page:039
SPECS: Steel. Approximately 4" (10cm) long. Includes .30-06
and .308 chamber spacers and complete instructions.