Here’s where things get slightly interesting. The SU16D12 is one the shortest and lightest of the SU16 line. The main difference between it and the SU16C are the 12″ barrel and compact forend. But they come at a price, because the SU16D12 is an NFA item and unfortunately tax stamps are still a thing. If you’re looking for an extremely light, compact and capable 5.56 short-barreled rifle, the D12 or D9 are for you.