This is HN, let's take the intelligent conversation up a notch:

If we look at firearm homicide, there is ratio of legal guns used to kill people and illegal guns used to kill people. What ratio is the saturation point, after which you gain nothing from stricter gun laws?

I think we can safely assume that some portion of people would like to own gun whether or not it's illegal. If we also assume that such people are likely to get illegal gun only if they know someone who has already bought illegal gun. Now we can also assume that there is certain tipping point, where illegal guns start to penetrate society disproportionally compared to legal guns. Also we can safely assume that illegal guns are used disproportinally in homicide, because it's so difficult to use them in hunting or sport. I think we should use the homicide rates compared to each other, because the actual number of illegal guns is always uncertain by definition. The actual total rates of firearm homicide are not very reliable, because they are influenced why what happens to be available weapon in a situation where homicide would happen anyhow. Also it seems that there are certain types of homicide cultures, which affect the situation considerably across time and space. Total amount of homicide and it's fluctuation is useless, because there is considerable time lag and the number and effect of different variables is unknown.

I don't know enough statistics to calculate it. But my gut feeling is that after 50%/50%, you have reached the tipping point. Also my gut feeling is that if I was police, I'd prefer something like 5 legal gun homicides against every illegal gun homicide. This way the legislation could provide some info how perps are armed in hostage situations etc. Also high amount of legal/illegal guns might help to regulate the caliber of guns. Which in turn would help to keep the police body armor effective.

We can also assume that organized crime benefits from overly strict firearm laws. They get their own partial violence monopoly plus income from smuggling.

On the other hand, is it even possible to calculate the opposite, too lax gun law? Now if the ratio of gun murders to other murders is very high, that has to rise some suspicion. Because we are particularly interested by gun inspired crime. Again my gut feeling is that above 50%/50% indicates something. Knives are always available, if murderers pick firearm instead, then firearms may be too available. But then again, murderer might opt fro firearm if there is possibility of the target to be armed. This gets tricky.

Police despotism? What is the ratio of police shooting a civilian to civilian shooting a civilian? Civilian shooting another gives indicator of general rate of violent crime. If police shoots lot's of people in a nation where crime rate is very low, that hints totalitarian state. What is the acceptable band of ratios?

For U.S. there is this extra "police comes and takes away my guns". My suggestion would be that give people licenses to certain calibers. Now police knows who and how people are armed, but they don't know the actual number of firearms in any ones possession. Which makes collecting all of them away impossible. Which means it's pretty dumb to even try, one person can own ten pistols, but can only shoot them one at a time.