actually you will have to check into it but I know Maryland it is the opposite.
Maryland is the same way. They still have an "assault weapons ban" of sorts. In Maryland it is illegal to buy or sell a magazine over 20 rounds. However it is not illegal to own one. Therefore you can go out of state and buy one and transport it on your person back into maryland as long as it belongs to you. However I cannot mail order one because that would be considered part of the purchasing transaction because I would be taking possession in Maryland. So If I bought one out of state and bring it back with me I am ok. If I bought it and forgot and left it at a friends house in another state and he mailed it to me or brought it to me the next time he visits and the tranbsaction was caught I would be in trouble.
So check your local laws. It may be it is only against the law to buy or sell and not against the law to own.