The MGD PM-9 was a French open bolt SMG, designed in the late 1940s or early 1950s by Louis Debuit and manufactured in small numbers by French firm Merlin and Gerin in the 1950s. The PM9 was an unusual design in three different ways: it employed off-axis delayed blowback, it had a clock-style spiral mainspring similar to that of the Lewis gun, rather than the cylindrically-coiled spring used in the vast majority of self-loading firearms and, most unconventionally of all, used a rotating flywheel as a delaying mass in conjunction with the bolt.
en.wikipedia.org/wiki/MGD_PM-9
Don't try to recreate what you see in this video, as this is gameplay. This video was created using the game World of Guns:
store.steampowered.com/app/262...
This game is also available on Google Play, App Store, Amazon and other platforms.