Yes, because they wouldn't be "illegal" where you bought them, unless you went to somewhere like NY to do it. Bringing owned magazines into MD is not "importing" so it is legal.
Stating the obvious for the casual reader, laws may differ on this by state.
Jim's Rules of Carry: 1. Any gun is better than no gun. 2. A gun that is reliable is better than a gun that is not. 3. A hole in the right place is better than a hole in the wrong place. 4. A bigger hole is a better hole.
no guns = might makes right