Weigel explains the current state of affairs:
One of the NRA’s greatest legislative successes, the Firearms Owners’ Protection Act, let dealers sell ammo without recording vital information about the buyers. That law eventually facilitated the online ammo market, which allows sites like CheaperThanDirt to sell 30-round extended clips for $8.99.
Ambers explains why ammunition control could work:
If you frequent "Survivalist" websites, you'll find that one of the most pressing topics discussed is gingerly called ammunition life span management. Ammo has a shelf-life. Even good ammo. Guns are forever, but ammo degrades, even if stored in precisely proper conditions and humidors that criminals don't often have.
Subject ammunition purchases to the same scrutiny that goes with gun purchases. An instant background check. Slow down the process. Obviously, the more lethal a bullet is, the higher the justification to regulate.
Earlier Dish on bullet control here.