I visited the Military Museum in Wrocław, Poland, and came home with some interesting additions to my photo album and for TFB’s Photo Of The Day. My Polish is a bit weak, but if my findings are correct, we’re looking at a Polish wz 43, which was a licensed production version of the Soviet SG-43 Goryunov, chambered in 7.62×54mmR. This particular example represents a specialized variant with a curved barrel, a modification undertaken in post-war fortifications to enable firing around corners from fixed defensive positions without exposing the gun crew.

The curved barrel allowed gunners to defend from narrow gaps or embrasures in underground bunkers and fortified posts, probably a tactical necessity in Cold War contingency planning along Poland's borders.

The curved barrel makes you think about the barrel life: the curved path should accelerate wear and the projectiles endure stress as they traverse the bend. However, in the calculus of a fixed defensive position expecting brief, violent engagements, a shortened service life was probably an acceptable trade-off.

The gun would likely fire only during the few hours of actual combat before the position was overrun or relieved.

The curved barrel makes more sense if you study this diagram and how the machine gun was mounted underground.