Item is source controlled by oem us army armament research, dev. And center, benet labs watervliet, new york cage 1nuw7.The only authorized source identified is beldam crossley ltd, united kingdom, part number 1663
A metallic or nonmetallic circular item specifically designed to be placed at the breech-block end of a gun barrel chamber for sealing against powder gases. It is also used to seal against powder gases between a projectile and the gun barrel.
Classification: Parts and accessories of military artillery weapons of 9301.11 or 9301.19
NSN 6150-01-475-8481
NSN 6320-01-373-9355
NSN 6610-01-555-8364
NSN 6620-01-254-3609
NSN 6220-01-164-5228
NSN 2925-01-400-2286
NSN 5960-01-599-9821
NSN 6650-01-364-8504
NSN 5920-01-484-4168
NSN 5930-01-112-1803
NSN 5835-01-412-0344
NSN 5925-01-085-4355