Finishing an AR9 build from Palmetto glock lower and 4" upper w/ 2" KAK can from their pre-Christmas sale. I have a SIG brace but have read recently that if I shoulder the brace then I would be breaking the law. I have a valid CCW and most of my shooting is done at a public indoor range that I am a member of so don't want to open myself up to having "law issues". My question is can I shoulder the pistol with just the buffer tube, or cannot shoulder it at all. Is the shockwave treated the same as the sig brace in that it can't be shouldered? Just file SBR paperwork and put whatever stock on it I want when approved? As always, I appreciate all feedback. Thanks.