Today's citizen-soldier would carry an AR-15 or variant. If there's one modern gun protected by the 2nd, that's the one.
What does a typical modern day infantryman carry as part of a standard kit?
Not Javelins and anti-personnel mines, those are application- and mission-specific. A soldier doesn't just show up at the armory and load up with whatever high explosives they want; they have a standard issued set of gear, and then mission specific gear divided up among the squad.
Armored infantry transport with mounted machine gun and or cannon turret? Anti-air counter measures? I have no idea how that fits in an individual soldier's kit. At a minimum, they're not bearable arms.
It doesn't mean all those other specific items aren't protected, but if you want an answer on an item-by-item basis, I don't know what to tell you.
My actual opinion on the matter is that we need a national conversation and some sort of constitutional convention to decide more definitively what the purpose(s) of gun rights should be.
Note that I said “what purpose” rather than “what rights”. I think a lot of people (not everyone, but most) skip this part and go straight to “I want to own select-fire rifles” or “large capacity magazines should be banned” before answering what the allowable purposes of private gun ownership should be.
I think if we enshrine in the constitution the right to own/bear arms for enumerated purposes, that the details will naturally just fall out from that choice.
Some examples of what we could choose from (mix and match to your liking):
1) There is no purpose for private gun ownership of any kind.
2) People should be allowed to own guns for private museums/galleries; historical/scientific/artistic collections.
3) People should be able to own guns for sport target shooting (Olympic shooting, IDPA, etc)
4) People should be able to own guns for hunting.
5) people should be able to own guns to defend their homes.
6) People should be able to own guns to defend themselves when they are out and about.
7) People should be able to own guns to bolster national armory against foreign invasion.
8) People should be able to own guns to attempt to overthrow their own government if they deem it necessary.
For example, if someone picked only something akin to #2, then likely guns would have to have firing pins and/or parts of the trigger mechanism removed.
If the people chose to allow guns for sport, perhaps the government would store your privately owned guns for you at sporting facilities.
If the purpose of private gun ownership is to empower citizens to overthrow a tyrannical government, then no registration process should be warranted for destructive devices like javelins or SAM batteries.
It sounds like your limitations match most closely with #7. In which case it seems like if that was the ONLY purpose for private gun ownership it would be reasonable for the government to store your guns in their own local armories and allow you to pick them up in they declare a national defense event.
If purpose of private gun ownership is to allow me to defend myself when I’m out and about, perhaps I should be allowed to carry a pistol when I’m at the bar. While I’ve never personally been in a situation where I’ve said “You know what would have made that go better? If I had a gun.” … I’ve only gotten in situations close to that when I’ve been out drinking late at night. Not allowing me to defend myself at my workplace, school, or bar kind of defeats most of any personal protection objectives.
If the goal is to only allow home defense, perhaps we only need to allow long guns (rifles, shotguns) and can still ban handguns. Perhaps every casing could be serialized and every transaction recorded and annual inspections done for storage conditions and safety adherence.
