Actually they could ban military small arms cartridges, doing something such as this would dry up lots of firearms very quickly. This has been brought up in congress before, but went nowhere. With the new UN treaty they want to push, instead of going after the guns themselves, all they have to do is attack the ammo.
Even the current listing of small arms ammo the military has in storage ranges from .22lr to .50cal. Inbetween these are, .22 hornet, .32acp, .380acp, .38spl, .357mag, 9MM, .40SW, .45acp, 5.56, 7.62(30-06, 308), 300WM, 338Lapua. This is just a few, there is lots more. I myself am more scared of something like this than an actual gun ban. Shotgun gauges are also on this list.
Even the current listing of small arms ammo the military has in storage ranges from .22lr to .50cal. Inbetween these are, .22 hornet, .32acp, .380acp, .38spl, .357mag, 9MM, .40SW, .45acp, 5.56, 7.62(30-06, 308), 300WM, 338Lapua. This is just a few, there is lots more. I myself am more scared of something like this than an actual gun ban. Shotgun gauges are also on this list.