Probably the best actor in this generally good cast is Warner Richmond -- the brawn heavy! Taking nothing away from the others, Mr. Richmond is almost likable, for a bad guy, and shows more personality than anyone else in the cast.
Then, for something else almost completely different, there is a story of, as someone titled his review, "prisoners in the desert." Not what we expect in a cowboy movie.
Johnny Mack Brown was, even from his silent movie days, a likable, good-looking guy, and capable of good acting, but in "The Courageous Avenger" he is not given much need of it.
He handles the action just fine, as the athlete he was, but mostly he is called upon to be brave and strong.
There is a lot to like in this film, but it seems long, even at less than one hour, so maybe some tighter editing would have helped.
And the stunt work was rather primitive for 1935. Yakima Canutt had not yet taught the entire movie industry how to stage a fight scene.
There is some good stunt work, though, including a Yakima Canutt type of being dragged under a rolling wagon. Note: the directing here was better than, for example, the first Indiana Jones movie, where Indie was dragged under a truck, but his clothes don't get torn or even dusty. Robert N. Bradbury was, therefore, a better director than whoever did "Raiders of the Lost Ark" (whatever happened to that guy?) because you see our hero mussed and dusty.
"The Courageous Avenger" is probably more interesting than exciting, but it is definitely that and I certainly am glad I saw it. I recommend it to you, too, and you can see it at YouTube. Unfortunately, the print I saw is only mediocre, but still worth watching.
This is added a couple days later: At least two reviews wonder why the bad guys use silver bullets, but that IS explained. It was, in fact, a perfectly good explanation by the chief bad guy.