Anyone else think the covers are a great guide? The style is consistent, and they usually have the series name prominently displayed. Later prints might even have a 'A Jericho Quinn Thriller' banner with a number. Always check the cover and copyright page before trusting an online retailer's listing.
The publication order is the chronological order, thankfully. No weird prequels released years later that mess up the timeline. What you see is what you get: a clean, linear story of Jericho Quinn’s career. I wish more thriller series were this straightforward. You never have to wonder, ‘does this book slot in between three and four?’ Nope. It’s a straight shot from one to eight. That simplicity is a huge selling point for me when my reading time is limited.
The series order is listed on Goodreads and the author's website. 'Savage Country' (2012), 'The Outsider' (2013), 'Brigade' (2014), 'Target Lock' (2015), 'Stone Cross' (2016), 'Field of Fire' (2017), 'Weapon of Vengeance' (2018), 'Tom Clancy Shadow of the Dragon' (2020) – though that last one is a Jack Ryan universe crossover.
Stick to that list for the pure Quinn experience. The crossover is fun but exists in a slightly different continuity.