Rem - if we interview most BG's we find that their primary source of firearms is from relatives/friends/neighbors (likely includes fellow gang members) and illicit street sales. Few buy their guns from an FFL.
The street sales are most likely stolen guns from a burglary of some kind. Some will show up that were "bulk" purchased by a strawman who turns them over to someone for street sales.
So laws limiting how many guns one can purchase are of very limited value in fighting crime since most BG's get guns from other sources. But there will still be a clamor for limiting sales to unscrupulous "gun runners". Since some states already have one-gun-a-month (OGAM) laws to prevent this, it can be shown that this is not the least intrusive limitation on exercising our 2A rights.
Certainly it'd be better to remove the restriction entirely, but pragmatically, I think that might be a more difficult challenge in court. Hell, I think we ought to scrap the 1968-GCA completely, but I know it's unlikely to happen all at once.
Ergo, we show an alternative solution that is less burdensome on the law-abiding and specfically interferes with those most likely to be trying to violate the law -- those people buying large quantities of guns.
Hugh_Damright -- I'll disagree with your statement because it infringes on how often a person can actually exercise their right to acquire a firearm.
(Art I, Sec 13).