BARREL EROSION STUDY OF RIFLES, 5.56MM, M16 AND XM16E1 - A JOINT ARMY- AIR FORCE TEST
SPRINGFIELD ARMORY MA
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Twelve rifles, 5.56mm, XM161E1 were fired to the end of their barrel bore service life. Measurements of the barrel bore were taken periodically with an air gage, and an expanding mandrel gage. It was determined that the maximum acceptable barrel bore diameter would be 0.2206 in. The barrel bore was considered serviceable for either overseas or CONUS use if that diameter had not advanced forward of the origin of the rifling further than 3.625 inches. Advancement to 6.625 in. was considered the cut-off for CONUS use only, and advancement beyond 6.625 would constitute complete rejection of the barrel. Gage, Barrel Erosion C7799792, designed by Springfield Armory, is recommended for this purpose. Test procedures are described and results discussed.