Regulated means regulated, and the current definition works just as well as the historic definition.

The gap is that you're assuming regulated means regulated by the Federal or state government. It does not, and in fact if you learn about the Bill of Rights, you'll find the intent was to guarantee the protection of rights the founders thought were natural civil rights. The core Constitution and Bill of Rights do not grant rights to the citizens; they recognize those rights as inherent and set limits to the powers of government.

The Federal Government intended to provide for the training and armament of the population. What happened was that after 70+ years of organized militias (the founding years through the Militia Acts), our governments realized the professional soldiers were far more effective in fighting wars, and cut funding to the militias. It's still advocated - see the Civilian Marksmanship Program - but neither mandatory nor comprehensive.

Gun rights activists like to point to Switzerland, and they are right except for one issue: in Switzerland, every conscripted citizen does get a fully-automatic assault rifle, but at the same time, that person is also trained in citizenship, ethics, military discipline, and handling of their weapon. But how do you think Switzerland would be in 150 years, if all other things stay the same, they were to continue providing assault rifles, but stopped educating?

The issue with your approach is that it still allows someone to get close to the school while armed. The solution we found in the military was the concept of remote Entry Control Points. You don't do much other than move the scanner and entrance a few hundred (or thousand) feet away from the school. The military doesn't even typically even have to build fences to keep people from skirting around the ECP - they just shoot anyone who happens to go over a particular painted line. (You wouldn't want to do exactly this at the school, but the point is that it doesn't need to be complicated or expensive). But, even if we did that, we'd stop in 5 years, because with an ECP, you wouldn't catch criminals, you'd deter them, so there'd be no evidence they were working, and they'd be defunded eventually.

There's a good point that if the school administrators had been armed, it's not that the attacker would have been shot down, but that he would have never tried in the first place. The concept is that he went for the softest target, and that if there were no soft targets, he might have killed just his mother and himself. The compromise is to find a way to keep malls and schools from being soft targets without arming everyone.

Manually reloaded? I'm not sure what you mean.

The Ruger Mini-14 is a typical hunting rifle, semiautomatic action, that uses magazines that are similar to NATO STANAG (they look like AR-15) but lower capacity.
The Remington 1100 is a typical hunting shotgun, semiautomatic action, capable of firing 00-buckshot, where each shotshell contains 8+ pellets, each potentially lethal on a human-sized target.
The Uberti Revolving Carbine is a fancy black-powder muzzleloader, suitable for hunting, that can fire six .44-caliber shots before reloading, thanks to a revolving breech (like a revolver pistol). And it's not even Federally a firearm, since it doesn't use fixed ammunition.

These three weapons are also specifically identified as hunting rifles in the expired Assault Weapons Ban. They are so far in the realm of intentioned and effective hunting weapons that they were called out.

And that's really it.

Older folks, generally, cost more.

In the US, (I'll make some numbers up, but depending on where you are, the proportions are correct) corporate hiring knows they can hire a rockstar out of college for less than $90k, or an average programmer for less than $70k. (Even as that rockstar is 3-10* as productive as an average employee). Why pay $120-50k for an average 45 year old engineer? They assume the experienced rockstars figured it out, started their own businesses, or otherwise moved into senior non-coder roles, and the aged coders are people who just couldn't cut it doing something else. So your software engineering degree isn't necessarily worth less, but if you expect to be doing the same thing with it at 45 that you did at 21, you have a surprise coming unless you plan very well. There are great ways of doing this - becoming a subject-matter expert in something rare, consulting, moving into a mentoring role, or working for companies that are less bottom-line focused (government/military-industrial complex). But there's a substantial number of software developers for whom there is someone else willing to try to do their job for less $. That's one of the big reasons for both unions and professional licensure, but that's another discussion.

This isn't unique at all to us. Any job enjoys this - "Step Up or Step Out". If you're an aging worker, you've always got to ask yourself what you provide that a college grad doesn't. (And hope you aren't asking what you provide that a HS grad doesn't, like many folks had to during/after the .com bubble). The canonical answer is "experience", but the professions show that isn't really true unless you can directly demonstrate it. More senior doctors in some fields are more prone to mistakes than younger doctors, because the senior doctors trust their "experience" whereas the younger doctors trust research. But the senior doctors also handle more patients, due in part to the same corner-cutting.

Option 1. Re-implement your legacy application on a modern platform, from legacy source code, or from scratch/reverse-engineering.
- You'll pay down your technical debt and possibly have a supportable, and maybe even virtualized, production system going forward.
Option 2. Sustain legacy equipment knowing that no modern emulator handles all the details of your particular proprietary hardware.
- Double down on your investment and leave the problem for the next guy.
Option 3. Hire IBM. (Nobody ever got fired for buying IBM).
- Mostly this will end up just like (2).

Oh, you wanted virtualization...but I think that's a solution to a different problem than the one you are facing. Get that app working on something reasonably open and then we can talk about virtualization.

This story shows up in Google's top 10 search results for me for Unisys Unixware right now, which really should emphasize to you the magnitude of the pain you might be facing...