Chasing That "Perfect" Barrel
The barrel is the heart of any rifle, the MK18 is no exception. As with any AR-15, there are a ton of barrels to choose from on the market. For this project I decided to have a 16 inch Colt barrel cut down to 10.3 inches, I had it laying around so I decided to save a little money.
There were two main reasons that I went with the Colt, I wanted chrome lining and I wanted a specific gas port size. Since this rifle is intended for hard use I wanted the increased durability from the chrome lining. Most 10-ish inch barrels on the commercial market have a .072 + gas port size, mil-spec for MK18s is .070. Factory port size for a Colt 16 inch M4 barrel is .062, I had it expanded to .070 to meet mil spec. As a result the rifle won't reliably cycle .223 ammo (unsurpassed).
So why all the fuss with gas port size? I shoot this thing 99% of the time surpassed, so I wanted the a smaller gas port than what is usually available on the market to help with gas blow back.
