So gun advocates, tell me how you would stop crime.
I'm not
exactly an advocate, but on the other hand I don't think flat-out bans are a good idea, and I think that arguments along the lines of, "If you're not planning to do anything illegal, you can't possibly need one of these guns, so you've got nothing to lose through this kind of law," are disturbingly similar to, "If you're not planning to do anything illegal, you haven't got anything to hide, so you've got nothing to lose from surveillance of your Internet activities."
So, here's what I'd do.
1) Simplify the system. Cosmetic and other arbitrary qualifications play too large a role, and can make it extraordinarily difficult to do something like getting a collection. Hire experts on weaponry, preferably foreign nationals* who don't stand to gain or lose significantly as a result of this legislation, to rewrite the rules to be simplified and be based on actual weapon capabilities. Provide as much scientific data as possible in order to allow relatively objective conclusions to be reached.
2) Simplify the system. On the other side of the fence, simplify work for the ATF and whatever other regulatory bodies you want to be involved. Give them the power to simply and efficiently carry out their duties - if nothing else, let them have an electronic, centralized database and require yearly audits. Don't institute arcane hoops and loopholes specifically to make it harder for them to do their jobs. Increase funding significantly - there need to be more agents, if nothing else.
3) Emphasize psychological profiling in gun purchases. Provided you have the basics (an address, no
violent crime convictions), the only barriers should be based on an assessed likelihood that you'll abuse the weapon, and your knowledge of relevant safety. Scrutiny should increase as weapon effectiveness increases, from a written questionnaire for a hunting rifle to full-on interviews for the heavy stuff. In general, if you're the sort of person who
wants an opportunity to use the weapon, you should be denied for anything but a hunting or other sporting weapon.
4) Electronic tracking systems, ideally sealed inside a weld in the weapon if manufacturing techniques will allow that. Obviously, criminals will learn how to disable these, but if you allow for an electronic "Report a lost or stolen weapon" page and make them difficult to remove, you can learn something from the data before it goes offline and frequently something about what was happening to it before it went offline. If it goes offline and such a report isn't filed within 24 hours, or whatever time limit seems reasonable, there should be criminal penalties for the purchaser (with allowances for extenuating circumstances like a kidnapping or whatever, obviously, but I'm pretty damn sure that'll be very, very rare). The time limit should be sufficiently short as to force owners to actively check on their weapons.
5) No guns may be grandfathered in, except for the electronic tracking system (which is going to be impossible to place in many guns without ruining them). Give existing owners a couple of years to do the necessary research and undergo the appropriate psychological testing, beyond what you give the market before the laws kick in.
6) Any time guns are seized from somebody who purchased them legally, compensation equal to the weapon's current market value needs to be given, and the government needs to pay for all the education and tests (whether for prior owners or new ones). This isn't supposed to be a plausible set of suggestions, obviously - there's no way you'd convince any government to shell out this kind of cash. But, given the necessary resources, this is how I'd do it.
7 (optional)) Uncap the system. Don't have a hard limit on the kind of weapon you're allowed to obtain. This one's iffy, and more about my own understanding of the future. Sooner or later, we as a society have to get used to the notion that technology will allow one person to cause untold destruction, and we won't be able to keep that technology under-wraps. Eventually, somebody's going to work out a way to print nuclear bombs, for starters, and if nanotech ever becomes a thing then we
really can't count on something like a ban. We need to work on creating societies where people won't
want to do these things, and that brings us to some very troubling problems with human nature that are really off-topic. The important thing is, bans give us a false sense of security on this topic and prevent it from being addressed.
*Do not, under any circumstances, tell the public you're doing it this way. Unfortunately, much of the vocal pro-gun crowd is the kind of group that will throw a shitfit if they think non-Americans are writing our laws. Bury them under a series of advisory committees and recommendations or something, and present the rules as originating from Americans whenever possible.