You must be 18 to buy a rifle. The stock has nothing to do with it.
A TRUE Assault Rifle is fully automatic. Federal law requires you be 21 to buy one of those in ANY state. However, what people may CALL an assault rifle (such as a semi-auto AK47) can be purchased at 18.
Have never heard of an underwater assault rifle. In the US, you must be 18 to buy a rifle, and 21 to buy a fully automatic rifle.
18 to buy a rifle or shotgun, 21 to buy a handgun or assault rifle.
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.
For a semiautomatic rifle, you must be 18. For a TRUE assault rifle, which is capable of burst or full auto fire, you must be 21. Federal law.
18
18 for a military style semi automatic. For a true assault rifle, which would be an NFA Class III full auto weapon, 21.
18.
18 is the federally mandated age so 18
Federal law is 18.
18