Barrel hardness, rockwell c scale 32 to 37; surface phosphate, mil-p-16232, type m, class 2; inside surface treatment is chromium, per 12913468
Classification: Parts and accessories for military rifles of heading 9301
NSN 5990-01-352-5255
NSN 6685-01-615-3111
NSN 6645-00-496-7424
NSN 4140-01-310-3330
NSN 5960-00-426-8028
NSN 5930-00-404-8999
NSN 5905-00-827-2875
NSN 6130-01-481-4119
NSN 6150-01-294-4483
NSN 5835-00-080-8213
NSN 5990-01-356-4259
NSN 6130-01-603-6816