So recently just completed my AR backpack pistol build. It has 7.5" barrel, coming in at a total of 21.5". Which it's considered a pistol (firearm). When I purchased the stripped lower I already knew what I wanted to build so I asked the FFL to register as a pistol. Was told they only see it as a receiver so that's what it is going to be registered as. I know it's not very practical to carry something like this around but you know America. I do have my LTC out of Philly. I've heard people say that the state does keep records of who owns handguns l, then I hear they don't actually. I looked into the law and nothing says it has to be registered as a pistol.

With all that said, my question is it against the law to carry this loaded it my car or on my person in a backpack of course? Will the cops go off of the dimensions of the AR?

I have asked a different FFL these same questions but instead of answering they said they would just carry a pistol. I know it's dumb but just want to know if I'm able to do this from time to time.