1. No one know how many guns there are in the U.S. civilian population.

From production and import-export figures we know how many new guns were added each year since WWII. That allows us to estimate the total civilian gunstock at between 285 and 300 million guns.

Note that this estimate does not allow for the following: a) how many guns have been destroyed through poor maintenance – but guns are highly indestructible; w/ minimum maintenance they have a practically infinite life expectancy; b) how many guns have been destroyed by police after confiscation – but most confiscated guns are just resold to the general population; c) how many guns have been covertly exported, e.g., the owner moving to Mexico w/ his gun or selling it down there.

2. Nobody knows how many guns are owned by the average gun owner.

There are roughly 95,000 guns per 100,000 American men, women and children. But this is misleading because not every one owns a gun. Survey evidence suggests that the average gun owner may own four or more guns. Survey evidence is inherently misleading, however. Many people will not admit they own guns at all. If we took survey evidence at face value there would only be perhaps 210 million American guns – meaning that tens of millions of guns that were sold have somehow simply disappeared.

It can reasonably be estimated that roughly half of American adults own at least one gun.

3. The anticipation that guns will be restricted inspires large increases in gun sales.

That is the consistent experience of at least 50 years. For instance, "assault weapons" sold poorly until bans were proposed. Then sales (and prices) greatly increased.