Speaking of ammo, when I was in west Omaha a couple of weeks ago I swung into Cabela's and bought a couple hundred rounds of 7.62x39 for my AK-47.
When I checked out, the gal asked for my phone number. Without questioning it, I gave her my phone number 'cause places are always asking for phone numbers, zip codes, etc. for marketing and market studies.
After I'd paid and walked out, it hit me. The government doesn't even need to track firearms, all they need to do is track ammo purchases. And I'm sure anyone buying any quantity of ammo for an assault type weapon would throw up a red flag.