Criterion Barrels AR-15 Barrel HBAR Contour 6.5 Grendel 22 inch Mid Length 1-8 Twist 5/8x24 Thread Stainless Steel Finish Black 65G22S-HB12. 223 Remington and 5.56 NATO at longer ranges the 6.5 Grendel has increased in popularity as an alternative...