I was shooting Cliff Swallows on the weekend, trying to get them in
the air. Shooting 1600 ISO, Tv at 1/2000, sunlight (aperture was
around f8-11), 300mm lens. Most of the time I was set at AI Servo AF
and automatic focus point selection, but foreground birds that I
managed to catch were usually out of focus. The 40D manual is not very
clear about how the focus settings work and what to use when. Any
suggestions?

Archibald