There is a potential "Military Thing " ( and not commenting or endorsing at this time, in this thread ). But that would potentially apply IF you were here under orders for temporary duty, and NOT intending to establish Residency in Md.
We understood from the initial post in this thread, you were talking about : 1. After leaving Military and 2. Intending to establish Residency. So that means all the usual laws, regulations, and procedures would apply.
Will you be attending that Gun Show in NC ? The odds of NC based dealer being knowledegable about the fine print of Maryland's Rifle Scheme are very low. ( Unless at the establishment where MDS senior member, and Maryland escapee August1410 works in the New Bern area .
Conversely , if make inquiry with a Maryland based, or Maryland adjacent dealer recomended in this thread, or otherwise an Industry Partner of this Forum ( IP) , they can tell you exactly what is Md legal . And probably be glad to sell one / build one for you, even as an NC resident.
If I were being cynical, I'd say a N.C. dealer made a sale that put a few bucks in his pocket, and when the boom drops on the customer, he'll be out of N.C. when it happens, so the dealer won't feel any real blow back...that's if I were being cynical.