But it seems to me that there are a few things we can all agree on:
- Criminals and irresponsible people shouldn't have guns
- Law-abiding/responsible gun owners (by definition) aren't a problem.
- There's too much violence committed with guns (which is, of course, precisely why many gun owners carry heat), much of which is preventable. Yes, violence is committed with knives and other weapons, but guns make it much easier to be much more fatal with less personal risk to the shooter than any other weapon, hence the focus on guns.
"Responsible", I think we can all agree, means never allowing a child to have access to a loaded weapon without appropriate supervision (and for very young children, obviously, it means never letting them have access, period.) This is not a 99% of the time thing - we wouldn't tolerate an airline pilot who avoids a crash 99% of the time, after all. It means 100% of the time you don't let kids near guns unsupervised. Take your kid hunting, show them how to safely handle it, go target shooting. But if your child gets access to your gun to take to school, or finds it and shoots a playmate, then you have to be responsible for that. If your 4 year old shoots your 6 year old, you are guilty of child endangerment, assault, and possibly murder. After all, kids can't be responsible, so you need to be. (Is this even controversial?) And if you suspect someone of suicidal thoughts, you should ensure they can't get your guns.
It may not be possible to prevent criminals that are determined enough and sophisticated enough from getting guns, but being responsible means not helping them to do so. This means when you sell a weapon to someone, you are comfortable that they are also responsible. You want to give a gun to your uncle Joe? Sure, why not. Sell a gun at a gun show? OK. But here's the thing: you need to be responsible for making sure that the recipient isn't likely to do something stupid. After all, if it's your responsibility to not help bad guys get weapons, then you need to exercise at least some care in making sure they don't.
I'd propose that if you give/sell a weapon to somebody, and they commit a crime with it, then you should be held responsible as an accessory to the crime. But I'd pair that with a "get out of jail free" card: if you perform a background check (or have one done on your behalf), then you are presumed to have done your diligence and have no responsibility whatsoever. You know your Uncle Joe, so you can decide not to do a background check on him, but selling a gun to Wayne who you just met at the gun show is probably a bit more of a risk. And it seems this should be transitive. If Alice sells to Bob who gives to Claire who sells to David, who commits armed robbery with it, and Alice was the only one who did a background check, then Bob and Claire should be accountable for allowing David to get the weapon. In other words, background checks would not be mandatory, but failure to do so has its risks, and you need to weigh them. Doing the background check is generally cheap insurance.
Many criminals also steal weapons, and others are lost. Arresting a bad guy and sending him to jail for possessing a stolen weapon is heck of a lot better than waiting until he hurts someone before arresting him. So part of taking responsibility for making it harder for bad guys to get weapons is reporting them as soon as you are aware of a loss or theft (ideally including serial numbers). Again, rather than making this mandatory, it's your choice. But if someone does something bad with your weapon, and you knew it was missing/stolen but hadn't reported it, you're effectively an accomplice and should be treated as such. Reporting it missing would, as with performing a background check, would absolve you of any such liability. Again, cheap insurance to do so.
Speaking of insurance, responsible people recognize when they have the potential for greater loss than they can afford. They can't afford if their house burns down, if their car crashes, or if they get cancer, so they carry insurance for all of these risks. Lawyers carry insurance in case of bad advice, doctors carry insurance in case of bad treatment. None of these are controversial, they're all common sense responsible things to do. Weapons - guns in particular - are quite capable of causing losses far beyond what an owner can afford; a responsible gun owner carries insurance. And like all policies, that insurance should be expensive for risky behavior and cheap for responsible behavior (think gun safes, training certification, etc.).
Finally, the words "law-abiding" in the phrase "law-abiding gun owner" needs to mean something. Obviously, speeding, cheating on your taxes, and mass murder are not violations of equal magnitude. But if you commit any crime of violence (or threat thereof), even without a weapon, or break any weapons rules or crimes involving a gun (including poaching or armed robbery), it seems to me that you've demonstrated that you are not a law-abiding gun owner and should forfeit your right to have one.
I don't offer any of the above suggestions as a cure-all for our violent society. It won't solve most suicides (a large fraction of gun deaths), and it won't prevent terrorists or mass shooters, who generally are sophisticated and plan meticulously. But it could help reduce the far too common daily killings.