I took a couple of my ARs out on Thanksgiving and noticed a few things shooting my 14.5" long-stroke piston and my 16" midlength DI. *The piston system has a strangely lessened felt recoil than the middy. Both used heavy buffers and the same ACS stock with enhanced recoil pad as well as PWS556 compensators. I was expecting it to be snappier/harsher than the DI but was pleasantly surprised. My observation was independently confirmed by four other shooters. *Even with a midlength, I was still getting gas face intermittently. This was obviously not an issue with the piston upper. *The DI was the more accurate of the two at 100yds. It did have the benefit of a free float rail whereas the piston system by nature was not.