With a general and an individual introduction to each story, here are a dozen roles currently culled from magazines -- Western Collier's, American Magazine Western Magazine and Famous Western -- and corralling knowns and unknowns. Emphasizing the trends away from the cornball stereotype this displays the cowboy and gunfighter, the Indian and the settler as more realistic figures, the motivation and plot and dialog as more plausible and effective. A novelette of a boy rebelling against home and family ties, a white man who lived with, and was loyal to, Indians, a prospector who could not kill, a Quaker who fought his way, a treaty kept with the Indians -- and more -- add up to a fresh, entertaining grouping. Among the familiar faces -- ycox, Guthrle, Brandon and Gulick.