A friend of mine has, completely by chance, been working on a Wild West RPG called Ballad of the Pistolero. I say completely by chance because the topic only came up when I was talking about my Devil’s Staircase Wild West RPG. The chances of two different developers writing wild west game at the same time has to be fairly low. It is hardly the most popular genre.
So a bit more about Ballad of the Pistolero… Foxwood Games tried to make a very cinematic action based wild west game but has included elements of Zweihanders d100 system in that mix. You can take a look at the test rules as there is a link to them near the bottom of the Kickstarter pitch. Making the test rules available is a nice idea as it does mean that backers get to know exactly what it is they are buying into if they support the pitch.
As this is a friend’s pitch I will particularly encourage you to take a look and lend your support. Not that I am biased at all!