In NJ, James Holmes likely would have been caught before committing his massacre

[MineralMan]

99. Someone who was determined would still buy the weapons, even

in New Jersey. He'd just buy them illegally.

That said, the easy access on the Internet to things like 100-round drum magazines, tactical ballistic gear and other items, does facilitate people who want to create mayhem. Most of the sales of that stuff are to people with firearms fetishes of some kind, who are unlikely to perpetrate such a thing, but easy access is easy access.

There's even a 100-round drum magazine for the Glock pistol he owned. Looking at it, it seems like a stupid, almost useless piece of equipment, really, but it's available for those who have $350 and a pressing desire to own such a thing. The photo I saw showed some guy in tactical gear much like this shooter was wearing, ready to take on all comers. Such situations are so infrequent that owning a 100-round magazine for a Glock seems pretty foolish to me. I cannot, for the life of me, imagine any real use for it, other than mayhem.

None of that negates that point that illegal purchases of firearms are also possible, so controlling legal sales to an extent needed to prevent this person, who had no criminal history and maybe no mental health record, would probably not meet 2nd Amendment requirements. Some states have very strict laws, but the weapons could still be acquired by anyone with enough desire, even in those states.