This is our 16 inch Mid Length Gas, light contoured barrel that is Melonite/Nitride treated. Melonite has shown to last 30% longer than Chrome. Please see our FAQ section for more info on this. This barrel has a Wylde chamber which is more accurate, but can still shoot .223 or 5.56 ammo. Barrel extension is re-torqued to the barrel after treating, due to different expansion/contraction rates. This is the proper way to treat a barrel. Barrel is milspec 4150 steel, has M4 ramps and is threaded 1/2×28. Gas block is .750. Weight is 1lb 8oz and has 1:8 twist rate with 5R rifling. If purchasing a bolt also, we will headspace to the barrel. Comes with gas port drilled and gas block dimpled at the bottom for easy gas block alignment.