I'm not very much familiar with WWII anti-tank weaponry, but I managed to identify this one as British QF6 pounder. Am I correct? It is situated in the Syrmian village of Susek, on the right bank of Danube. Syrmian Front saw very fierce and bloody fighting from fall 1944 to spring 1945. This gun was probably used by the Soviets or Yugoslav Partisans, acquired through US-USSR lend-lease program.
Syrmian Front - Wikipedia, the free encyclopedia