First, I should introduce myself as this is my first post on this forum. I have only just been directed to it, and it is filled with interesting material!
I have a particular interest in ammunition and guns, especially heavy automatic weapons. I have put quite a lot of information about these on my website.
The information about AAC guns is particularly useful, as I didn't know that they had managed to sell any of their guns. I have some documents concerning their activities, and they seemed to be much better at publicity than at engineering. Somehow they managed to give the impression that they were responsible for the 37mm M4 aircraft gun used in the P-39, whereas in fact this was a design of John Browning and was developed and built by Oldsmobile.
The photo at the top of the first post in this thread is clearly not of 37mm calibre, though - judging by the ammunition belt, it looks to be more like 20-25mm. As far as I know AAC made nothing smaller than 37mm calibre. So what was it? I have seen this photo before, and asked the experts at the British Pattern Room (who have a huge collection of weapons and an extensive library) what it was, and they don't know. Does anyone have more definite information?
Military gun and ammunition website: http://www.quarry.nildram.co.uk