SIG 516, 1-7 5.56x45 chamber, 14.5 inch chrome-lined barrel, 5 shot group around 1 inch at 100 yards. 25.2gr 8208XBR, LC brass (weight sorted, 93gr +-0.5gr), CCI400, BTO: 1.835, 2820 FPS. SIG M400, 1-7 5.56x45 chamber, 16 inch Nitride barrel, 5 shot group around 1.5 - 2 inches at 200 yards, but...