zero gun ownership rights

Well, I think that's true. But you jumped straight from that to universal disarming, which doesn't follow. Not having a right to a thing does not automatically ban the thing; it simply means the thing becomes a privilege to be granted or withheld/revoked. A driver's license works the same way: you don't have an automatic inherent right to a driver's license, but that doesn't in any way imply an agenda to revoke all licenses and ban driving.

Take, for example, nationwide reciprocity

Does nationwide reciprocity actually make sense? Plenty of things require re-licensing or re-certification when switching states, and yet we still manage to maintain quite good records on those things. So this:

could actually further your apparent goal of universal registration and background checks

does not follow from reciprocity. All reciprocity does is let the least-restrictive state set the rules for all states, and that's not going to help with making registration or background checks work.

Allowing new machine guns is also inherently palatable to universal registration and background checks.

Why do people need machine guns? With driver licensing there's a good argument to be made that in most areas of the country a car is basically a necessity of holding a job, being able to obtain basic goods like food, etc., and there are still a bunch of requirements a vehicle has to meet to be driven on the public roadways and a bunch of modifications that can make a car no longer legal. So what positive good is served by people owning machine guns, or the modded guns you keep bringing up? You've argued no logical connection between making these things legal and increasing the effectiveness of registration systems; that's on you to demonstrate.

Repealing silly state-level ankle-biting laws regarding mostly cosmetic features that make it more dangerous for the law-abiding to keep and bear arms would have a positive effect on national standardization, which could also lead to an improved case for universal registration.

Reforming the BATFE would go a long way toward not continuing to alienate the gun-owning public with arcane, cryptic rules that place one at the risk of felony for simple acts, and would again be easy to align to a case for registration and checks. Streamline, simplify, control.

Let's stick to cars for a moment because this hits an actual important point. We already live in a society in which strictly-enforced but largely arbitrary laws regarding cars, their registration, upkeep requirements and traffic rules are routinely used to put people into permanent life-ruining revolving doors of debt and incarceration.

And there's the rub: guns are not unique in this respect. Cars aren't unique in this respect. There are lots of these bits of awfulness which are used to selectively make peoples' lives hell, in all sorts of areas. So if you want to simplify complex codes that primarily get used for selective prosecution, or attack selective prosecution from another angle, then by all means do so. Just don't treat it as something unique to guns, and don't push it only in the context of guns. Because frankly, I'd much rather work to get a poor person out of endless fines, fees and jailings over a traffic stop than work to get you a machine gun. It might turn out getting that person out of fines/fees/etc. ends up getting you the machine gun you want, but I want to see evidence of you on board with the plan for a reason other than your own desire for the machine gun before I'll trust you on the matter.

What do _you_ view as a "reasonable compromise"?

First: giving up on the idea of militias rising against the federal government. If it ever became necessary, and if the military stayed on the government side, well, we're getting really good at taking out resistance from the safety and comfort of a control room hundreds or even thousands of miles away from the action. Some dudes with camo and rifles aren't gonna cut it. And if the military doesn't stay on the government side, well, the arms are gonna be available. So that one's right out, and I'd argue for repealing the Second Amendment entirely to make it crystal-clear.

Then: registered and tracked ownership of firearms, sale and possession heavily taxed along with tax on ammunition, no sales permitted without full strict documented background check, immediate confiscation after any incident indicating unfitness to own, mandatory requirements for secure unloaded storage at all times the gun is not in use, ownership limited to well-defined types of firearms, ownership solely for the purpose of collectibility/historical value or for sport, use restricted to areas explicitly designated for such purposes. No open carry, no concealed carry, and anyone who wants a gun for the purpose of shooting other people (and self-defense is "for the purpose of shooting other people") automatically forbidden to ever have one.

Worried that criminals will still illegally get guns? Well, we're already busy starting to decriminalize drugs, so let's find another use for that enforcement money and prison space and devote the same bloated budgets, paramilitary tactics and crushing mandatory sentences to going after illegal guns. Make illegal use or possession truly carry the kind of penalties drugs carry right now. Forget multi-strike or "career armed criminal" laws. Make any crime committed with, or while carrying/brandishing, a gun into a "hard 50" or even just life sentence, first offense. Harsh prohibition hasn't worked with drugs because they're addictive and lucrative and large numbers of people will work to get them no matter what. Imposing these kinds of rules on guns would still allow the "fun" people want them for (owning a cool collection, shooting down at the range, going on a hunting/camping trip, etc.), which is the typical problem with prohibition attempts. Raise a few generations with these norms and the ingrained culture of using guns as tools to solve problems (where "solve the problem" means "kill someone" to the person wielding the gun) -- which we certainly have in this country -- will fade into the history books.