Who is at fault when I buy an AR-15 Rifle from an online dealer in another state while I live in Virginia.?

Have it sent to another dealer in Virginia who knows and respects state law. 18 is the age to buy any rifle in Va. not 21. I lived in Virginia for many years, the gun dealer who has the rifle has decided to follow their own rules instead of state and federal law. Ask the dealer to show you the law that says an 18 year old cannot buy an AR in Va. He can't do it.