Did not know that the Republik of Maryland required guns to be registered.
They don't, it's voluntary. Although they keep records of purchases, they do not require registration of handguns brought in from out of state by residents who moved here. There are a couple of other ways that they do not have state records as well like building your own and buying a gun as an FFL. I have three that the state has no idea about; one conversion and two bought with an 03 FFL
Washington Post is notoriously ignorant of the RKBA and the need to defend oneself. The DA's here are also notorius about indicting homeowners for protecting themselves. But the good news is that out of the last three incidents I heard about a homeowner defending themselves in the last 10 months in the D.C. area of Md, none went to trial (well, I am nearly sure about two of them).