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Federal Law, 21 to purchase a handgun from an FFL (Federal Firearm License) dealer.
You may possess a handgun at 18 in WV, but you cannot buy one from a licensed gun dealer.
A gift, or a loan (or, when state law allows, purchase from a private individual) you are allowed to possess it. But you cannot buy a new, or used one from a dealer, if you are under 21.
All this assumes that you are not in ANY WAY otherwise a prohibited individual.