Text below from this site:http://www.nraila.org/gun-laws/state-laws/maryland.aspx
It would also be worth your wild to print the section of MD law pertaining to this issue, and carry it in the car. It can help the police who may be unaware, and also show you are trying to follow law.
CARRYING AND TRANSPORTATION IN VEHICLES
It is unlawful for any person without a permit to wear or carry a handgun, openly or concealed, upon or about his person. It is also unlawful for any person to knowingly transport a handgun in any vehicle traveling on public roads, highways, waterways or airways, or upon roads or parking lots generally used by the public. This does not apply to any person wearing, carrying or transporting a handgun within the confines of real estate owned or leased by him, or on which he resides, or within the confines of a business establishment owned or leased by him.
Rifles and shotguns being transported in motor vehicles must be unloaded.
A person may transport a handgun if they can demonstrate that the handgun is being carried, worn or transported:
To or from a place of legal purchase or sale, or repair shop;
Between a person’s bona fide residences, or between his residence and place of business, if the business is operated and substantially owned by that person;
While engaged in, or traveling to and from a target shoot, formal or informal target practice, sport shooting event, hunting, trapping, or dog obedience training class or show; or
By a bona fide gun collector who is moving any part or all of his gun collection from place to place for public or private exhibition.
During transportation to and from the above places the handgun must be unloaded and carried in an enclosed case or enclosed holster. An additional penalty is provided for any person convicted of unlawfully wearing, carrying or transporting a handgun, if his deliberate purpose was to injure or kill another person.
