[Juha]

Hello
a little bit more info
According to Zaloga & Grandsen USA sent to USSR 1000 M17s and 100 M15A1s, the latter had a open top turret with a 37mm AAAgun and 2 0.5” mgs. Now I have no problem with M15A1s but 1000 M17 was the whole production of that vehicle. US Army used M16 but M17 was based on M5 half-track, which was the main h-t supplied to British Army and the British 21st Army Group used some quad 0.5”, both towed M51s and SP versions, in NE Europe in late 44 onwards. That according to Routledge´s Anti-Aircraft Artillery 1914-55. But the book doesn’t say if the SP versions were M16s or M17s. Logistically M17 would have been better for the British Army but if the acquisition of the SP version was some kind of emergency measurement against low-level LW fighter bombers, and that was my impression of the reason of the British acquisition of quad 0.5”s when I read the book, then it is altogether possible that British got M16s, which was standardised equipment of US Army and based on M3 half-track (almost identical to M5 but from different manufacture and with different engine, IIRC). So in that case the 1000 M17s to USSR is altogether possible.

Also according to Zaloga & Grandsen no Soviet AAtanks saw action during the Great Patriotic War but there were some ZiS-5 lorries converted to the ZiS-42 which mounted a 25mm Model 1940 AA gun on the rear of the chassis. And also there where a small number of YaG-10 heavy lorries modified to carry the 76.2mm Model 1931 AA gun.

HTH
Juha