Jack"King" Kirby did more westerns than I thought when I first looked into it. While it's not a genre he's famous for, he seemed to have a good handle on the elements of showcasing the western landscapes and staging the action of gun play. Up top is the very first western cover featuring the King's artwork that I could locate, an issue of Prize Western. Below we have covers for Boys' Ranch, Bulls Eye, Wyatt Earp, Rawhide Kid, Kid Colt, Two-Gun Kid and more. Enjoy some vintage Kirby!
Historical Accuracy Update: Thanks to loyal Dojo reader Britt Reid I learned of an earlier Jack Kirby cover than the Prize Western cover which leads off this gallery. Here it is in all its glory.
Here is Hillman's Western Fighters #1 from 1948 -- it's a good one too.