As a followup to our mud testing, we took out AR, M1A, and MAS 49/56 to a dusty part of the range and used an air compressor to shower them with blowing sand and dirt while firing. Which ones would be able to keep running, and for how long?

You can see the companion piece on mud testing here: https://www.full30.com/video/9eef6b3a4eb6c8846a4c8dc4b8968bc4

This testing was inspired by archival footage of Owen SMG testing in WWII: http://www.t3licensing.com/license/clip/48050209_2200.do