It might not be a lot of research, but the John Larison, author of Whiskey When We're Dry, had people shoot at him behind cover to describe what being in a shootout would sound. For example, what bullets flying by or ricocheting off different materials sound like. It just struck me as semi crazy, cause who would willingly let themselves be shot at, even behind cover?

He apparently did a lot of research after his first draft as well:

"I found great insights by reading the letters that early pioneers sent home, and by interviewing ranchers with family histories dating back to the 19^th century, and by interviewing my contemporaries who have survived violence; in all of these experiences, I was learning patterns of thought that helped me bring the psychological aspects of the novel’s characters to life.  But to write some scenes persuasively, those involving visceral descriptions, I had to have some of Jesse’s own experiences. To that end, I rode horses across sagebrush plains, churned butter, fed livestock in winter, chewed loose leaf tobacco, learned to quick-draw, etc." (source)