B. M. Bower 
The Flying U Ranch [PDF ebook] 

This book is about a ranch called Flying U Ranch. Thousands of sheep invaded the coulee. The Ranch brings back a happy family of cowboys introduced in Chip of the Flying U.
A dated, but well written western yarn of the actions of cowboy ranch hands dealing with troubles with adjacent property-stealing sheep herders while their boss is away. At first it goes bad for the cowboys, but together they come up with a plan to attempt to get even and stop the take-over. All the characters and activities are believable. Some clever twists hold your interest despite the old-fashioned writing style.
The characters are believable and fun loving.