A large fraction of the harm from firearms comes from their ability to fire rapidly which didn’t exist when the constitution was written. As such it was making a very different balance of risk between the general public and individuals.
Very obviously individuals were expected to be part of the militia, which was the military at the time (c.f. the Militia Acts 2 years after ratification requiring individual gun ownership and very clearly laying out that all able-bodied white male citizens aged 18-45 were part of the militia), but also states could regulate weapons if they wanted.
Not a firearm.
I didn’t say we could ban compressed air powered guns, I specifically said percussion caps. The Girardoni was way less dangerous than a modern handgun.
In the 230 intervening years, we've vastly increased the scope of the federal government and developed a formal military, so one might argue we ought to amend the constitution to change exactly what's allowed under 2A (e.g. it should be straightforward to have a nuclear weapons ban added with unanimous agreement), but as it stands, 2A (+14A) clearly gives individuals the right to own the arms necessary to run a functioning ("well-regulated") militia, which in 2026 means at least semi-automatic firearms.
Thrown stones are a fast firing deadly weapon. They, compressed air guns, and ball musket etc aren’t used by modern military forces in combat because they are less dangerous.
A rule that allows compressed air weapons yet bans percussion caps is quite reasonable and could pass constitutional scrutiny.
Banding heavy machine guns yet another invention after the constitution was written didn’t, so there’s clear present this wouldn’t either.
Obviously there’s a bunch of exceptions, including as you point out the federal option of going through a background check and paying 200$/grenade. But that’s only at the federal level it doesn’t necessarily meet state requirements.
The rules on those background checks are as capricious as banning people who were dishonorably discharged from the military.
State laws are another matter entirely, but even many states with stringent gun laws don't ban DDs specifically (probably because many lawmakers are not aware that such things are legal).
As for the background checks, I own over a dozen NFA-regulated items including a destructive device (a 40mm grenade launcher), and I can't say that the rules aren't really any more onerous than they are for regular firearms. This particular bit about "banning people who were dishonorably discharged from the military" applies equally to any firearm transfer under federal jurisdiction, for example (e.g. buying across state lines, or within states that mandate a federal check for anything). As I recall, the only thing that stood out in NFA forms compared to the regular stuff was the need to submit fingerprints. That aside, it was smooth sailing even back when I wasn't a citizen. So really the only barrier is affordability, and AFAIK this is exactly how the NFA was intended to work back when it was designed ($200 was about 4x the price of a full auto gun like Thompson back then, so it basically made them outlandishly expensive, only available to the rich).
A far looser restriction.
> doing the associated paperwork for the feds.
That implies that it’s guaranteed you will pass, which is false.
That said, the ability for some states to totally ban ownership outside of military or police rests on them not receiving constitutional protection.