Found this pic while browsing the NASA website:

Website details:
Quote:
Date: 10.01.1940
Title: Brewster XF2A-2 Buffalo
Description: Brewster XF2A-2 Buffalo: The Navy's Brewster XF2A-2 Buffalo benefited from Langley's experience in drag reduction. After initial testing at Langley, it was returned to Brewster in June, 1940, and is seen here in the 30 x 60 Full Scale Tunnel following its return to NACA hands in October 1940.
ID: EL-2002-00619
Other ID: L24843
http://nix.ksc.nasa.gov/info?id=EL-2002-00619&orgid=1But it looks like a shot of a (presumably trial) four gun wing to me, which I'd never heard of, and I can't imagine would've been much good - weight and spread of fire.
(There's a high res version linked or downloadable at the address above)
Anyone got any details?