Anybody know of a publisher this guy could use?

Clayton Cramer is a writer. He has written something like 4 other books. He's having trouble finding a publisher for his latest work. He believes it is because it is about the history of guns and gun ownership in America. I believe he may very well be right. Anybody know of a publishing house that might be a bit more 2nd Ammendment friendly? If so, give him a shout and let him know of them.