It's not about whether it's threaded or not here in Maryland, it's about barrel profile which translates into weight. Barrel profile + minimum overall length (29½") are the basic parameters here. It's unclear at the moment if a heavy profile barrel that has been fluted is legal. I suppose it'll take a court case to decide that issue.
A 16" barrel under most circumstances will meet the length requirements. All of this is moot for those rifles which pre-existed here before 2013 when these draconian regs were put in place- if you have a lightweight shorty it had better have a pre-2013 serial number on it too, if caught with it.
As bad as it sounds here, it's not really all that horrible. The LGS's are full of myriad styles of AR's, parts, ammo, etc. Plus, we booted out the Socialist Progressive governor we had back then and installed a moderate Republican who is making all the right noises and instituted reforms to balance the scales in many areas of life here. There is hope for the future.
