138 .22lr rim thickness gauge

Measures .22 lr rounds
Rounds are placed in a hole and the gauge moved until it stops
Once gauged the round is placed with others of the same mark
Once batched, rounds have identical head-space and therefore be held in the breech in an identical position prior to firing - immediately improving each batches' ballistic consistency
This critical process is necessary to improve scores by paying greater attention to the smallest detail - sometimes a simple rule even forgotten by the best