None. When made, 99.9% are legal, no matter where made. Just because it's against the law for YOU to own it doesn't make the weapon illegal. Technically the above is correct however as guns are not required to be registered in all states it is impossible to say how many are owned legally. Guns that are owned illegally are obviously not registered so there is no way to know how many there are.
As many as you want.
As many as you can afford.
As many as you want, provided you're legally able to own them.
It is estimated that the number is between 35 and 45%. Since most states do NOT require that guns be registered, it will have to remain an estimate.
There is no limit.
4594
No limit
@ 1/2 of the population does not own a firearm.
4 or 5
50% of california
You'd have to ask them to find out.