I don't know, there are obvious choices. Do you have any suggestions? In Canada it's done through licensing fees, but there is a shortfall that is made up by the taxpayer.*
Ok, here's the problem. Let's say the "fair price mechanism" that you refer to is a measly $500, which - as any gun owner would know - is a ridiculously low price to provide for a firearm. But let's go with it to keep the argument simple. For every 1 million firearms turned in or confiscated, you're talking half a billion $$ in money paid out. So it really ends up being how many of the 330 million or so firearms you believe are bought back. Could be anywhere up to 165 Billion dollars. Licensing fees? Please. There will be absolutely zero political will to spend that kind of money. Ever.
By definition, the answer has to be "No". However I do believe that over a period of years, say twenty or so, virtually all illegal weapons would be discovered and taken out of circulation. But naturally there will always be a small number. Probably within a relatively few number of years the majority of illegally held firearms would be located. Of course the argument that there is no point in regulating firearms because the regulations will only affect honest people is illogical. Nevertheless we will continue to hear it.
So in 20 years you believe the impact would be felt. I have to disagree. I mean, we made drugs illegal and I can go down to the local high school store this very minute and buy some if I wanted to. All you're going to do is raise the street price of firearms. Not to mention that, without a national gun registry (and we don't have the ability to register all the guns out there right now) many of those legal guns will end up in circulation among criminals eventually, when the price gets right. Additionally, criminals will maintain firearms a lot better, extending their life. Lastly, right now you can 3D print a pistol. I can't imagine what 20 years of technology will do.
Your ban will have very little, if any, effect.
This will happen spontaneously over time, as those with non-complying guns try to use them, acquire parts or ammunition for them, as their neighbors report them, and are arrested, or as they die and leave them to heirs that are compliant. And some will be stolen and then recovered. We don't see many machine guns on the street these days, but we know there are a few out there. The idea is to decrease the number of non-compliant guns used in committing crimes. And banning machine guns did this in the interim before they were replaced with legal semiautomatic assault rifles with bump stocks. There is an entire support system behind guns -- it is the manufacturer, the gun maker, the ammunition supplier, the dealer. Pinch of any of these elements and you make it much less inconvenient to get your hands on particular gun types. As those who would acquire these guns, despite restrictions, are forced into clandestine activities to acquire them, the probability of their being caught can be expected to increase.
Machine guns were addressed in 1934. It's quite a different world now. There weren't hundreds of millions of machine guns on the market back then. Additionally, a machine gun is less effective than an AR15 platform due to recoil and a whole host of other factors. It would be like banning a specific type of hammer used only on an exotic aircraft vs. banning all hammers.
These semi-automatic weapons you refer to don't require special ammunition for the most part, and even if they did, reloading is very easy with the right kits. All you'd do is drive up the price of ammunition.
Feel free to respond to any of these points. I hate to rain realism on the great ideas, but none of these ideas presented thus far have any chance of working in the real world.
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*An MMT (Modern Money Theory) economist might argue that it can be done at no real cost, and even a net savings. I won't bother with the argument here but you can google MMT economics, or go to YouTube to find out what this very fascinating, school of economics is all about. Randall Wray, the Univ. of Missouri Economist, a Hyman Minsky protege, is an example of an MMT economist. I'm mentioning this to you as I know you are into corporate finance. I think you would find this stuff interesting reading. It is not non-sense by any means.
Right, no real cost. The ban on all gun sales removes $33 Billion from GDP (without considering the buyback spend), and approximately 200,000 employees from the workforce - and that's just the workers that work directly for manufacturers and direct gun sales. It doesn't count all the folks in the gun retail environment, shooting ranges, sportsman clubs, gun smiths, pawn shops,....whatever.
As time goes on, the price of illegal weapons on the streets skyrocket. Weapons begin to be smuggled in through the border, and legal residents go out and acquire an illegal firearm to protect themselves from the criminals that have them. I know I would. I'd get a pistol and keep it safe in case I was ever attacked in my home. Better to be judged by 12 than carried by 6, right?
People begin to be arrested for defending themselves with an illegal firearm, and subjecting normal law abiding, otherwise harmless individuals because they now own an illegal gun after you took their legal one away. Meanwhile the criminals using guns continue on their merry way - because if I'm a criminal and I'm going to commit murder (which might incarcerate me for life), why do I care about your silly gun law?