'Well-regulated', in the eighteenth century vernacular, meant 'well trained'.
Alan Keyes knows original intent far better than his critics here.
I smell desperation.
Yeah, Luis is extremely worried that, like drivers licenses,
these wouldn't be made available to illegal immigrants.
Not quite correct.
It actually referred to efforts to ensure that the militia groups carried similar equipment. Training was a goal, and the militia did "Drill" fairly often.
But "Well Regulated" mainly referred to efforts to ensure that each militia member in a particular band had their weapons in the same caliber (bore diameter) and lock type.
This made it much easier for members to share ammunition (flints, bullets, patches, and powder) if they were called to fight.
So far as I know no one was forced to buy new equipment of a different caliber if what they had was not the local standard, but they were encouraged to do so.
In modern parlance it could be argued that "Well Regulated Militia" means that all American males of militia age should be expected to own a fully automatic M-16 rifle in .223/5.56 caliber and a Beretta 9mm pistol.