A person must be at least 18 years of age to purchase a rifle or shotgun. To purchase a handgun from a licensed firearms dealer, you must be at least 21 years of age, pursuant to federal law. For statutory regulations concerning underage persons possessing firearms, refer to Virginia Code §18.2-308.7, possession or transportation of certain firearms by persons under the age of eighteen.

§ 18.2-308.7. Possession or transportation of certain firearms by persons under the age of 18; penalty.

It shall be unlawful for any person under 18 years of age to knowingly and intentionally possess or transport a handgun or assault firearm anywhere in the Commonwealth. For the purposes of this section, "handgun" means any pistol or revolver or other firearm originally designed, made and intended to fire single or multiple projectiles by means of an explosion of a combustible material from one or more barrels when held in one hand and "assault firearm" means any (i) semi-automatic centerfire rifle or pistol which expels single or multiple projectiles by action of an explosion of a combustible material and is equipped at the time of the offense with a magazine which will hold more than 20 rounds of ammunition or designed by the manufacturer to accommodate a silencer or equipped with a folding stock or (ii) shotgun with a magazine which will hold more than seven rounds of the longest ammunition for which it is chambered. A violation of this section shall be a Class 1 misdemeanor.

I want to buy a gun that is semi-auto and it doesnt have a threaded barrel, therefore cannot be equipped with a silencer, and has a magazine that holds 10 bullets. base on that context its considered just a rifle correct? which means any 18 year old person can buy it right? but if I purchase a magazine that holds more than 20 it becomes an assault rifle right? so legally if I don’t buy a magazine that holds more than 20 bullets before I’m 21, I can legally buy and own the gun as long as it doesnt hold more than 20 bullets?