I was at my LGS yesterday browsing and noticed a completed M&P 15 lower for a couple hundred bucks. I've been Googling all day but haven't found an answer, so I figured you guys could help me out before I go back next weekend. Assuming it is pre 7/20, if I were to buy it for a build, would I have to abide by the MA compliant rules (i.e. fixed 10 rd mags)? Sorry in advance if this is a dumb question, thanks!