Are ak-47s legal

AK-47's are not illegal in the US. In fact, I myself own one. You have two basic categories when dealing with AK-47's: Fully automatic, and semi automatic. The semi automatic version is treated like any other semi auto rifle, and is legal to purchase and own, although some states or cities may have bans on them for certain reasons.

The fully automatic version can also be purchased and owned privately, but you have to jump through a few hoops for it. You must pay a $200 tax stamp, and then wait for BATF (Bureau of Alcohol, Tobacco, and Firearms) to approve you.