The Handgunlaw.us entry for Maryland has been updated to reference the Oct 1 change in statutes for the magazine restrictions.
Higher Capacity Magazines:
(These new Restrictions on Firearms and Mags becomes effect October 1, 2013. The Bill can be seen Here
a semiautomatic centerfire rifle that has a fixed magazine with the capacity to accept more than 10 rounds;
a semiautomatic pistol with a fixed magazine that can accept more than 10 rounds;
“detachable magazine” means an ammunition feeding device that can be removed readily from a firearm without requiring disassembly of the firearm action or without the use of a tool, including a bullet or cartridge.
This section does not apply to:
a .22 caliber rifle with a tubular magazine;
A person may not manufacture, sell, offer for sale, purchase, receive, or transfer a detachable magazine that has a capacity of more than
10 rounds of ammunition for a firearm.