I believe the gun in the pic is a Soviet 76.2mm field gun, possibly the later Model 1943 from memory. The upper part of the shield folded down IIRC for the AT role, in which the Soviet 76mm guns were quite effective, so much so that they were widely used by the Wehrmacht (Pak 36(r)being their designation), including mounted on one of the many Marder variants.
When you soar into the air in a Sopwith scout And you're scrapping with a Hun and your gun cuts out Well, you stuff down your nose till your plugs fall out 'Cos you haven't got a hope in the morning!
