Capitalism is great at reducing friction, but reducing friction for something that is used for killing is not something that makes for a healthy society.
Interestingly enough, the AARM actually increases friction instead of reducing it. In most states, anyone can buy ammo without any oversight, and we're not even talking about online sales. The AARM requires matching ID with Facial recognition and appropriate age for purchase. This is a case of capitalism doing exactly the opposite of what you were saying.