In the US, 18 for rifles and shotguns, 21 for handguns.
In the United States, you can legally purchase a gun at the age of 18 from licensed firearms dealers.
Hand gun - 21; long gun - 18
It depends on your meaning of "have". To purchase a paintball gun the legal age is 17. Though if you have an adult present, you may purchase one at any age. So in theory, a 2 year old could have a gun.
21
To purchase a gun, no. Anyone can purchase a gun as long as they meet the age requirement, aren't a felon, and don't have any disqualifying misdemeanors.
In the US, legally you have to be 18, illegally there is no age limit.
18 for long gun, 21 for hand gun
There is no restriction on age for a sight in the USA.
Since you posted the question on the internet, do an internet search on Maryland gun laws.
18 or 21 depending on if you are buying long gun or hand gun ammunition
Assuming you are of legal age to purchase, black powder or smokeless powder for reloading can be purchased from gun shops. Yes, proof of age is required.
The legal age to buy a gun depends on the type of gun it is. For an example, to buy a rifle or shotgun(excluding assault rifles) you must be 18 years of age. To buy a handgun you must be 21.