Dead Six by Larry Correia and Mike Kupari
This is an upfront adventure story. Two groups of very skilled killers, one a group of mercenaries, the other a group of ruthless thieves. Both end up in a small Middle Eastern country and their missions often put them into conflict. Lots of action, very accurate weapons description and handling, shadow agencies, and grand conspiracies. I really enjoyed this book, a fun read with plenty of action and twists.