Off the top of my head I can think of several reasons to register guns that have nothing to do with confiscation:
- If guns are registered to owners, you can hold people responsible if they sell their guns to criminals or crazy people. Currently there's little responsibility on the part of an individual selling a gun, and that's how the majority of criminals get their guns. This would make it much easier to spot and arrest those who are providing their weapons to criminals.
- If police had a database telling them that you are legally carrying a licensed concealed weapon when you're pulled over driving, they would be prepared with this information after running your plates and before walking up to your window. Less chance of surprised, misreading an action you take, and seeing a threat that isn't there.
- It would be possible to check if someone who is newly diagnosed with Alzheimer's or other mental issue has weapons. Then the family / caretaker of that person can be informed to keep an eye on them.
I can think of two problems with the bolded point above:
1) There are already plenty of laws regarding straw purchases, i.e. if you knowingly buy for someone who has lost their right to bear arms (felons). These laws are seldom enforced.
2) Such a measure would be hilariously easy to bypass. You need a serial number in order to trace a gun, criminals have an aversion to being caught, and criminals are more than willing to file the serial number off the gun (which is also illegal, but they're criminals, right?), so actually back-tracing a firearm through its chain of custody would be impossible.
Take out all the suicides. Take out all the law-enforcement related shooting (setting aside that disarming the police is a real conversation I'd like to have at some point, what would it take to get that to happen and lets do that). Take out all the shootings by criminals who were already not allowed to have guns. Look at that number of homicides compared to elsewhere. And then ask would you rather someone come at you with a gun, or a bomb? The knife argument is a red-herring. The total homicides statistic is a red-herring. At best, legislation could impact how many unlawful shootings are committed against another person by law-abiding citizens. It's not fucking many. I'll grant that it is probably nonzero.
I've actually done the research on this for you, so I can provide some numbers. These are from the FBI crime statistics, and they're approximate, but pretty representative:
1) There are about 10,000-12,000 homicides* per year, and about twice that many suicides, committed with guns.
2) About 75-80% of those murders are gang-related. Gang members are not law-abiding citizens, to gun laws won't affect this number.
3) That leaves about 2,000 homicides.
4) Police are responsible for about 1,000 of those, and nearly all are classified as justified. More gun laws will likely not affect this number significantly.
5) That leaves about 1,000 homicides per year by non-gang civilians*
* - this number includes justified homicides
Now I do not wish to minimize the tragedy that homicide is for the people involved, but in the big scheme of things
it's really a statistically tiny problem.
BTW, there's no accurate count, but estimates peg the number at about 350 million guns in the US and 100 million gun owners.