Check For Worn, Out-Of-Spec Gas Cylinder
Helps determine the cause of unreliable cycling or if the gas piston
must be replaced with an oversize head. A precise reproduction of
the original ordnance gauge, 1005-222-05, that lets you easily
determine if the gas cylinder mouth, or power stroke area, is out
of round, or worn beyond specifications.
Big Book Catalog, Issue:66, Page:487
New Product Supplement, Issue:552, Page:008
SPECS: O1 tool steel. Hardened to RC 60.