I've played "At Close Quarters" and I really enjoyed it. Seems about right for the level you want to play. Bigger games could get unwieldy, what with the motivation system and the fact that you have to do spotting checks every time you want to fire (though you can do suppressive fire without aiming).
It is sort of billed as a modern special forces game (which is how we played it), but you could actually use it for any 20th or 21st Century conflict really, with or without special forces. In fact the new game "To the Last Man" by the same author uses the same core system.