[11Bush]

Thanks for the reminder of the water jacketed 50 cal. As soon as I started reading your post I remembered seeing this configuration on the early models. I think, and this goes back a long time, that they were/are on one of the battleship museums that my parents took me to when I was a kid.

[yarddog]

On page 177 of "John M Browning, American Gunmaker" there is a picture of Browning firing the .50 cal. in Colt's pasture in Hartford. The picture was taken in September 1918.

The gun is a water cooled model.