Hi. This is the AA gun Bofors 75 mm Model 29. Done with the help of german engineers, the genealogy of FlaK 18 acht-acht can be traced to this gun.
M29 was the backbone of sweedish AA during WW2 years. One of the first foreign customers was Finland, the guns were used with the british Vickers M/34 FCS with good performance during Winter and Continuation wars. The Bofors gun was one of 4 types of heavy AA of KMT Chinese Army (together with Vickers Model 31, FlaK 18 and soviet 76 mm M1938) in the long second sino-japanese war. Finally, The Hungarian Army used M29 in 80 mm caliber, alongside with well known Bofors L60 and FlaK 18. Cheers.