1).22LR – used to train soldiers, cadets, kids. Its used in biathlon, and other marksmanship competitions. Its used daily and around the world to rid us of pests, and hunt small game for sport or food.
2)12gauge – used by half the police of the world. Used for large scale hunting. Massive quantities expended in sports like Trap and Skeet.
3)7.62x39 – AK-47's. Warzones. 3rd world dictatorships. Active Mercs. Warlords, Cartels. Terrorists. Communist nations. Former and unwilling Communist nations who can't afford to switch yet. Civilian SKS owners! Large expenditures in combat, training and replenishing warstock.
4)9mm – used by nearly all militaries and police in nearly all countries for both handguns and SMG's, now the majority of newer handguns owned for defensive use are 9mm. As popular as .40 and .45's are in America and Canada, they are barely used anywhere else, and in tiny quantities.
5).308W/762N – heavy use in hunting, target competitions, civil battle rifles, police/military sniping. Military GPMG's still used for vehicle armament, especially helicopters.
6).223/556N – all Western and modern armies. Civil AR-15 owners. SAW/MINIMI burns up huge quantities. Varmint hunting.
Personally, I'd like to see more cheap 9mm, 12ga buck, .bulk or surplus .308W/762N.