AeroShell 33MS Grease
AeroShell 64 (previously 33MS) aerospace grease that meets mil-spec MIL-G-21164D for barrel nut and receiver extension assembly on AR platform upper and lower receiver threads. As used on complete Umbrella gov/military sample builds, offered here in .5oz or 1.4oz for your own barreling and lower building projects. Unless you run your own shop, the small jar will likely be the only one you will ever need. Consider yourself a pro-builder? Get the larger size for all those rifles you're working on. If in doubt, buy both and give one to your buddy*. Included with all Umbrella Upper Receiver purchases.
*Not suitable for personal lubrication.