From Max Popenker, we have a set of photos of a very funky German submachine gun from the first world war (presumably 1918). The weapon is currently in possession of the weapon design department at Tula State University in Russia, and that’s where these photos were taken. Until now, the only photo available of this gun was this one:

Well, it turns out that the gun in that picture is missing its feed box, which is a pretty important part, and tells us a lot about how it worked. The gun actually fed from a multi-column clip which held 8 rows of 10 cartridges each… When first loaded, the first column of cartridges is engaged by a sort of rack and pulled up to the chamber one by one. After the 10th round is chambered, the entire clip is stepped to the right so that the second column of cartridges is in position to be fed upwards. When all the rounds have been fired, the now-empty clip is pushed out through a slot … on the right side of the feed box.

https://www.thefirearmblog.com/blog/2015/08/04/mystery-german-ww1-sub-machine-gun/

https://www.forgottenweapons.com/experimental-german-0818-maxim-smg/