Betiobob, the F4F-4 had a third gun outboard of the wing fold
Nsclcctl, Grumman made F4F-3s and F4F-4s. Once Grumman was ready to begin the manufacture of F6Fs, General Motors began manufacturing F4F-4s and subsequent variants as FM-1s and FM-2s. In British service the F4F was called the Martlet before being renamed Wildcat.
Also, if you think the F4F looks like a beer keg, you should look at the Brewster F2A Buffalo!