Found what I was looking for in the WW2 aircraft with LCG in the nose.. Bell P-39 had a 37mm firing through the rotor hub. Don't ask me how.. just what it says... knew that I saw something on one somewhere... Not may built, and I know there were some in service in PAO.. met an old timer at church years back that flew them, then transfered to P-38 Lightning. He was on the Yamamoto raid flying top cover for them. Funny old guy too... said he was shot down three times... but got five of them.. "Oh your an ace." says I. "That's not how my wife pronounces it." says he.
FB
http://www.militaryfactory.com/aircr...ircraft_id=140