Suppose I find a 7.5" 300 AAC upper that I want to buy for future installation on an AR 5.56 pistol that I don't have yet. I own several other AR Carbines/Rifles with 16" and 18" barrels. The question is the legality of possessing an upper of that length without owning a pistol lower or a stamped SBR to attach it to.
I plan on getting a complete AR 5.56 pistol in the near future. If I also purchase the 300 AAC upper so that I have the option of using either on the pistol lower, then I will have at least one very short upper in my possession that is not attached to anything, but could hypothetically be mounted on a carbine lower. Of course, I wouldn't, but am I looking at a potential problem here, or over thinking it?
I plan on getting a complete AR 5.56 pistol in the near future. If I also purchase the 300 AAC upper so that I have the option of using either on the pistol lower, then I will have at least one very short upper in my possession that is not attached to anything, but could hypothetically be mounted on a carbine lower. Of course, I wouldn't, but am I looking at a potential problem here, or over thinking it?