You must be 18 years old to purchase or possess a gun in Tennessee. However, you must be 21 years old in order to purchase ammunition.
At least 18 for rifles and shotguns.
21
Hand gun - 21; long gun - 18
21
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.
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.
18 for long gun, 21 for hand gun
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
18 for long guns 21 for hand guns.
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.
To legally own a long gun (rifle or shotgun) in Tennessee, you must be 18. To legally own a handgun in Tennessee, you must be 21.
Please specificy what you mean by "permission." If you are of legal age, you don't have to have anyone's permission.
In most states you must be 18 to purchase a BB gun.