So Ive been around alot of ar15 and m4s and have decided that its time i get away from my ak's and get into the market for 223...What i cant figure out is whether there is any benefit to an ar15 rifle over an ar15 pistol... If I buy the pistol then I have a registered pistol lower, which means i have no need to buy a short barrel upper and $200 tax stamp. Also I could, for some crazy reason, carry it fully loaded in my vehicle. If i want the accuracy I can just get a long barreled upper and even put a stock on the pistol lower...IS THERE ANYTHING WRONG WITH THIS IDEA????