How can someone be in possession of ILLEGAL AMMUNITION?
Well for starters, you can't take all the rhetoric that you hear from prosecutors to heart.
They'll say whatever they want to make their case seem justified.
When you hear that statement it usually means that the guy is a felon or something and can't
possess guns or ammo.
Again, it may have something to do with his non-citizen status,
or some other obscure law attached to the registration of hi cap weapons in MA.
So what, show me a law that states he can not own a large amount of ammo... GL
I don't know of one and don't think there are any.
IOW, the Feds or BAFTE could declare that owning 20k rounds of x39 is a terrorist action. After all, they are deciding who is a terorist, so why not decide on what grounds you become a threat?
In the link posted, I have a feeling that this guy was being watched.
They never mentioned why he was pulled over
and from what I see on the shows about the FBI or DEA,
when they're ready to make a bust (pretty sure the guy is dirty),
they let the local police pull the guy over for not using his turn signal or whatever,
that way the guy doesn't suspect he is being taken down as part of a well researched sting operation,
then if they find something (which they're almost sure they will),
they use that for a reason to call in the DEA or BATFE, then the real investigation begins.
It looks like the police were just lucky to have pulled the guy over when they did,
when it is really the end of a long drawn out investigation by the BATFE or FBI.
As far as the original question of the OP,
unless there is some sort of "city ordinance" or local "fire codes",
you should be able to own as much ammunition as you can afford.