Going back a bit here, and the Judges point in the decision to refute the low round capacity argument that only 2.5 rounds are fired in the average gun fight. He pointed out that in Colonial times each gun owner was required to have a minimum of 20 rounds of ammo.
I have been reading up on the troubles in the Middle East, in particular the husband and wife who hid their infant twins and tried to defend their home with their legally owned weapons.
The problem was Israel LIMITS a private gun owner to 50 rounds of ammo, so as a Husband and wife they MAY have had up to 100 rounds of ammo.
BTW Israel just fast tracked their licensing process and raised the limit to 100 rounds.
If you are in a fight for your life against terrorists trying to get into your home, 100 rounds isn't going to cut it IMHO.
IMHO this is why you need a thousand rounds of any defensive caliber that is in your SHTF plan.
If you have other guns that are not your defense guns, and you only have a couple of boxes for each gun/caliber, fine
But if your SHTF plan is a AR rifle and a pistol of some type ( and here is where I fear for you in MA) you should have 10 magazines loaded for the rifle ( 20 or 30 round PMags) and for your pistol ( Glock 17 for example) you should have 10 magazines loaded and ready to go at a minimum, for a total of 1000 rounds of ammo for each, if not more.
There have been times when I have thought "why do we have so much ammo, what a waste of money" , but after the events of last weekend I think everyone should look at what they have on hand for ammo and mags for their primary weapons
I am not some crazy with a tin foil hat, I'm not a conspiracy theorist, but in light of recent events, even though they happened on the other side of the world, has me thinking that it would not take much for the same thing to happen here sometime in my lifetime.