We've got links to the Maryland laws at [URL]http://communities.msn.com/TheMarylandAR15ShootersSite&naventryid=100[/url]
Technically we don't gun registration (except Assault Pistols, which are registered), but the State Police keep records anyway. Since we don't, your friend won't need to register anything. I can't find anything in the law dealing with bringing existing weapons into the state. There are lots of rules for buying, selling and transferring NEW weapons.
Essentially, Pistols and non-Hbar AR-15's (and some other rifles) are considered [b]Regulated Firearms[/b]. New purchases are limited to 1 per month and a waiting period. Private sales must go through an FFL and the State Police check.
Weapons must be stored where kids under 16 can't access them.
He can call the MSP Licensing Division at 410-799-0191