Here is a FAQ From the MD State Police:
How can I legally transport firearms within / through Maryland?
Answer: They must be unloaded, in a carrying case, holster with a flap and the ammunition should be separate. It would be best to keep the unloaded weapon in the trunk where you do not have access to it. There are further regulations but essentially you can only transport a handgun between residence, to and from a repair shop, a shooting sporting event, between a residence and place of business if substantially owned and operated by the person. For more information please contact our Licensing Division.
They state Handguns in this but it is under the Rifle/Shotgun FAQ'sNew York, Mass and NJ are more stringent on their laws/rules on transporting. You just can't keep it in your vehicle.
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