I ordered a PPS 43 SMG kit and am trying to find a semi-auto receiver to make it legal. My question is, do I need a license to make this a working gun? I read on a website (ATF, I think) that you don't really need any kind of license to build one, if you are not going to sell it and have it in semi-auto only. Anyone know about kits or what I'm asking? PS: I didn't know if I should post this here, since I'm asking a question towards the pros or anyone who knows about my question.