Normally, any 9mm Tactical Carbine would be good for such a situation. But, If the SOB is wearing Body Armor. They need to teach these guys to take head shots, then arm them with 9mm Tactical Carbines and Pistols. The only issue is if the SOB takes hostages and uses cover, etc... A Rifle should rip through the cover, but has too much penetration for normal use. Possibly arm the average Gaurd with an MP-5 and M9. Then have some snipers with .308 Rifles, just in case.