The Mariners have sleeve insignia (over the cuff of a sleeve). On both sleeves. See table uniforms fleet that I gave above.
As the sailors were worn on left arm a sign of their marine specialization.

Sleeve Insignia Officers.

Sleeve Insignia sailors.
http://www.rkka.ru/uniform/terms/shtati_vmf.htmSleeve Insignia sailors by specialty.



German captured weapons (machine guns and submachine guns), willingly used in the Soviet army. German machine gun was perfect, the best similar weapon at the time in my opinion. Submachine gun was easier for the Soviet, so it is fun to use reconnaissance units. Furthermore, it was easier to get ammo in the enemy rear for captured weapons.
In addition, the Soviet sailors are widely used Soviet automatic rifle SVT-40.
By the way. Machine-gun cartridge belt used by sailors as a bandolier with a deficiency of conventional ammunition bags. And yet it was a tribute to the "seaman" fashion ...