The Maryland law only applies to handguns. I think most manufacturers now supply a fired case, even for those weapons not bound for Maryland. But yes, in the transition period, this program did slow sales, which is presumably just what was intended.
We also have a new law this year which requires one to sit through a 2 hour "safety" video in order to be able to purchase a handgun. We also have a 2+ week waiting period for handgun and restricted weapon (so-called "assault weapons") sales. And a discretionary CCW system. And a magazine limit.
It's so much safer now here in "The Free State" ...