I've run into a slight conundrum concerning the propeller color for P-40Bs. According to the Airfix instructions, the propellers were "metal" on the front and black on the rear. This is fine, except I have been unable to find exactly when the propellers were switched to black on both sides. Did this occur before Pearl Harbor, or after? Also, what was the color of the anti-glare coating on the back? I have run across a reference that indicates it was more of a dark "maroon" rather than black.
To complicate matters, the famous Life photos of the P-40 assembly plant taken in early 1941 actually show some of the P-40s with black propellers with yellow tips.
https://www.flickr.com/photos/35963591@N00/sets/72157622864527612/
I'm wondering if these could be the aircraft for British service?
Just trying to nail down the most likely colors before applying stencils. 
Gary