I read the first one Pecos Crossing. It was kind of boring but perked up at the end. Two young cowboys care for a man's cattle during the winter. They go into town to get paid. The guy pretends not to see them and walks off. When confronted on the sidewalk he claims he already paid them and takes advantage of the passing sheriff to claim the cowboys are trying to scam or rob him.
Cowboys end up in jail overnight while cattleman skips town. Cowboys head off the stage, force cattleman off, demand their money. Cattleman pulls a gun and accidentally shoots the young, newlywed wife of a recently resigned Texas Ranger. Ranger vows revenge. Cowboys hit the trail. Story follows the cowboys as they visit family, come to a girl in aid, etc.
The interesting part was when the story followed the Ranger who had been sick of work and hates killing. But, he is bound by his vow, reputation, and past life to carry through. A mostly happy ending.
I read the first few pages of Shotgun and gave up.