Cartridge gauges are furnished for gauging aircraft ammunition before loadin it into tho machine-gun belt or magazines. Every roun should be gaugged for over-all length and diameter, also depth of primer. Any rounds which do not check within the limits should be, discarded since many machine-gun stoppages are due to defective ammunition.

The .30-caliber cartridge gauge consists of three separate gauges. (See Figure 50.)

Operation.-The cartridge is breeched in gauge No. 2 and the fit is examined. Gauge No. 1 is then pressed against the base of the cartridge, which checks the length and diameter. Gauge No. 3 is then applied to the base of the cartridge and checks the depth of the primer.