Wait, are we talking about the mainline Tom Clancy series or the spin-offs co-written with other authors? The chronology gets muddied because some books are set before 'Dead or Alive' but were published later. For a pure Jack Jr. timeline, start with the prequel elements in 'Locked On' that establish his recruitment, then proceed with the order I've seen on fan wikis. Honestly, I usually just read them in publication order and mentally rearrange the flashbacks.
The definitive order, verified across multiple sources: 1. Dead or Alive, 2. Locked On, 3. Threat Vector, 4. Command Authority, 5. Full Force and Effect, 6. Under Fire, 7. Point of Contact, 8. Line of Sight, 9. Oath of Office, 10. Shadow of the Dragon, 11. The Red Rabbit, 12. Zero Hour, 13. Weapons Grade. It's a modern thriller series that's easy to follow in terms of order, if not always in terms of its dense technical descriptions. Publication order is king here.
Honestly, just use Goodreads. Search for 'Jack Ryan Jr.' series, and the list will come up with all the books in the correct series order, often with user reviews that tell you which ones are worth your time. The crowd-sourced data on that site is more than adequate for solving this. Half these comments are just rehashing what's already meticulously catalogued there.