Yes, you can obtain this achievement while waiting out the timer in cover. It will -POP- at 0:00. You won't get the XP from the Hit, but you can still get the $$$ so you shouldn't forfeit the Hit. I would recommend you just shoot them after the timer runs ouns out, and you should do this achievement early on in the game so you don't miss out on a large amount of XP or $$$. Questions or comments are welcome. If you have something negative, please let me know B4 voting so I can update and/or fix the solution.