Buchanan's Seige

Thomas Buchanan, who runs The Pictorial Arts blog, occasionally posts a cover image featuring his western alter ego, Tom Buchanan, from the Buchanan series published by Fawcett/Gold Medal and written by a number of fine western writers, including William Ard, Brian Garfield, and others. This particular image was posted by Thomas recently for this post, "Under Seige." The Buchanan cover paintings are usually pretty good, and I really like this one. Identifying the artist's model is easy -- the ubiquitous Steve Holland -- but I'm not sure about the artist. There's something about the moment of captured action and the pose with its particular details that reminds me of Neal Adams' work. But the only book covers of which I'm aware that Adams did are the Tarzan covers for Ballantine Books. So, anybody know who this artist might be?