Looks like when moving to the state you have 90 days to register regulated firearms aka handguns and “assault weapons.”

I have an HBAR ar variant. I am unclear if it needs to be registered, since Hbars are carved out of the banned list.

Second, and more nuanced: it says they must be registered if one intends to be a resident. If one is merely here for a year and has no intention of changing residency (military) to maryland, is there a legal precedent that handguns etc don’t need to be registered?

Military and NOT changing your HOR. As I understand the LAW, you are not a MD resident and don't have to resister shit. BUT you can't bring "banned" weapons into the State. I am not a Lawyer, so talk to one.

https://mdsp.maryland.gov/Organization/Pages/Automation.aspx

e-mail/call questions here:
Licensing Division via email at:  [email protected]​ or call us at:  410-653-4500.

Go over here and read around or join.

https://www.mdshooters.com/