I like Force on Force (I helped play test it an wrote up the section on tactics in the rulebook) but not everyone does. It can be hard to grasp and some folks just won't 'get it'.
There are some other rules out there. Ganesha Games has 'Flying Lead':
http://www.ganeshagames.net/index.php?cPath=1_10&osCsid=gjneqdc8ipec1nbd8fj049uf80
Brent Spivey's 'Battlefield' may work:
http://www.wargamevault.com/product/102355/The-Battlefield-Miniature-Modern-Warfare?sorttest=true&filters=0_40201_40011_0
This looks interesting but I' don't have it:
http://www.wargamevault.com/product/135451/No-End-in-Sight-Cold-war-and-modern-platoon-combat?src=slider_view&filters=0_40201_40011_0
Specific to Afghanistan but could be worked for other theaters is Skirmish Sangin (mentioned above)
http://www.wargamevault.com/product/109666/Skirmish-Sangin?sorttest=true&filters=0_40201_40011_0
There are a few other sets out there as well. Cold War Commander and other sets generally geared towards larger scale engagements using smaller scale figures could be modified a bit to work for example.
Automatically Appended Next Post: Honestly, at the scale of battle you seem interested in, differences in hardware don't matter all that much. Getting smacked by a 5.56 or a 7.62 will both ruin your day. Coming up against a tank with a 120mm gun vs a 125mm gun won't make much of a difference.
Just my opinion.