Kevin i agree with you that our lenses is to slow .. because it is driven by the camera.
You should look at the 50-500 Sigma lense for Pentax that just came out. It has a highspeed motor build into the lens.
I don't have a special technique. Shoot in AV. Try and get your shutterspeed as fast as possible. Use AF.C to focus. Shoot as many shots as possible while panning the bird. You are bound to get at least one shot in focus if you do this.
Practice on large birds. I gave up on smaller birds.
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Cheers
Philip