A visit to Larry Correia’s Monster Hunter Nation site had this forthcoming book listed. I am always up for a weird western. The form has pulp roots with stories by Otis Adelbert Kline, S. Omar Barker, and Arthur J. Burks in the pages of Weird Tales and Strange Tales. Robert E. Howard wrote a handful of stories, enough that he is often credited with founding the genre.
Joe Lansdale resuscitated the genre with the anthology Razored Saddles (1989), his fiction including Dead in the West, and his comic work on Jonah Hex in the 1990s (with Tim Truman).
Larry Correia’s story is the earliest setting for Monster Hunter Nation.
Amazon has Straight Out of Tombstone listed for a July, 2017 release. The price is listed as $11.07, so this is probably going to be a trade paperbacks. Baen is producing the best themed anthologies the last few years.
Forward David Boop
Bubba Shackleford’s Professional Monster Killers Larry Correia
Trouble in an Hourglass Jody Lynn Nye
The Buffalo Hunters Sam Knight
The Sixth World Robert E. Vardeman
Easy Money Phil Foglio
The Wicked Wild Nicole Kurtz
Chance Corrigan and the Lord of the Underworld Michael A. Stackpole
The Greatest Guns in the Galaxy Bryan Thomas Schmidt & Ken Scholes
Dance of Bones Maurice Broaddus
Dry Gulch Dragon Sarah A. Hoyt
The Treefold Problem Alan Dean Foster
Fountains of Blood David Lee Summers
High Midnight Kevin J. Anderson
Coyote Naomi Brett Rourke
The Key Peter J. Wacks
Fistful of Warlocks Jim Butcher