Illinois resident AR lower transfer question
I'm an Illinois resident but am going to school in Missouri. Recently, I bought a stripped AR lower and had it shipped to my gunsmith friend here in Missouri who has an FFL. I found out today, however, that because the receiver falls into the "other" category, I have to have it transfered to an FFL in Illinois, because technically it can be made into a pistol and thus, the special pistol transfer laws apply. My question is: Can I have my gunsmith friend attach a stock to the receiver so that it technically becomes a long gun? As I understand it, once a stock is attached, the receiver is classified as a long gun forever.
I'd like to not have to ship the receiver to another FFL and wait for the next time I'm in Illinois to pick it up. Is my idea feasible or am I just going to have to suck it up?
Thanks for the help.