Referring to rifles in this case, since that was brought up.
Rifles weren't brought up in the OP or my answer to the OP. So how the hell am I supposed to know that your question referred to rifles?
My original reply (that you commented on) was with regards to a carry permit, thus I was referring to carry permits and handguns.
You want to ask about rifles laws, then ask about rifle laws. Don't ask a murkey question in a conversation about handguns and carry permits and expect an answer on rifles.
As for Baltimore and Rockvile, with regards to rifles, they can't be carried period (open or concealed), and DNR forbids loaded long guns in vehicles, and DNR forbids loaded magazines with long guns.