If you own an AR, you cannot have in your possession a shorter than 16" barrel UNLESS you have a lower dedicated as a pistol lower OR you applied, paid for and received an NFA stamp. Otherwise it can be misconstrued by BATFE as you intend to have an SBR.
When I built mine, I ordered an Anderson lower and had it shipped to my FFL. When I went to pick it up, I checked OTHER on the 4473, and because we have to register pistols with MSP I had him fill out the pistol reg. form. Once I had that and turned it in, I then was able to purchase the upper legally because at that point I had a "pistol" lower.
IF you have to register pistols in VA, I would get the lower prepped and registered as a pistol before proceeding to the next step.
I went 10.5 on my upper that I picked up at PSA, it's a blast to shoot, fairly accurate so far at 100 yds with a Primary Arms red dot on it.
