Thanks to Jonathan Ferguson and Royal Armouries Archivist Philip Abbott, we have a compilation of some archival video of the E.M. 2 testing circa 1951/1952. This is mostly high speed video clips showing reliability testing, plus drop tests and other "rough handling". At the end, there are a series of clips of test-firing rifle grenades (the framing unfortunately crops out the grenades themselves), and then the coolest part - Stefan Janson himself dumping about a hundred rounds through an E.M. 2 as fast as he can.

Janson, of course, was the rifle's designer. A Polish expatriate working in the UK, his was born Stefan Januszewski, but Anglicized his name when he lived in England.