Just a store policy or state?

[RouxGaRoux]

In Louisiana, at what age can someone buy an AR or AK? I know it's 18 for long guns and 21 for handguns but I also heard that someone under 21 can't buy a rifle if it is capable of holding more than 5 rounds in a mag. I think this is an Academy policy but I'm not sure.
Thanks.

 

[charlie12]

I would guess it's a store policy and not law.