This is my replacement 350 Legend upper from BCA (16" M4 profile, rear charging, m-lok). The first one arrived FUBAR, and went back. Results below are 5-shot groups off a stable bench and Lead Sled DFT II @ 100 yards. I only took about 20-30 seconds between shots with these: Winchester 145gr FMJ: 3.99" Hornady 165gr FTX: 1.69" & 1.87" Hornady 170gr SP: 2.36" Federal 180gr SP: 1.86" & 2.45" I ended up doing some handloads (23.3gr and 23.5gr) of Winchester 180gr over H110 and clumsily mixed them up. That said, the first group came in at 1.35". Second group had a statistically significant flyer (it didn't fire on the first trigger pull) without that flier, the group would have been 1.00". The thinner barrel heats up pretty quick. I gave the handloads 1-2 minutes between shots.