Here is a post I made in another thread.
Check out this Faxon 18" barrel with rifle gas and light weight profile if you haven't chosen one yet.
http://faxonfirearms.com/18-gunner-5-56-nato-rifle-length-4150-qpq/
It was only in stock at Faxon for one day but several resalers have it in stock now for 5 to 10 dollars cheaper.
Properly set up is making sure the gas pressure is right for the weight BCG, buffer and ammo you will be using.
If the gas port is not the right size you may need an adj gas block to get the reliability you need.
For example I will be using a .5 ounce buffer and an 8.8 ounce BCG for a total of 9.3 oz. (low mass 3 gun setup)
Low mass needs less gas and full or heavy mass needs more gas.
Other folks might run an 11.7 oz M16 full mass BCG with an 5.4 oz H3 buffer totaling 17.1 ounces, almost double what I am.
Big difference in the gas required to operate these two extremes.
This barrel has a .081 dia gas port while others may have .093 or larger.
Here is a post I made in another thread:
Quoted:
Quoted:
I must ask why the 18? What can a 18 do that a 16 can't? Or are you just building a different look?
Only 2" longer than my 16" middy and I get a rifle length gas system for softer recoil impulses which is my main reason for switching.
It will also give a slight improvement in velocity and long range accuracy and is only 4 oz heavier at 23 oz..
It will go on a 3 gun build, the 18" with rifle gas is fast becoming the length of choice in that competition.
This really is an awesome barrel design with grade A quality for $189.
Faxon says this:
"The GUNNER (all caps, as it is that awesome) is the pinnacle of performance, weight, balance, and value. Designed by our competition shooting staff for those who value performance and versatility, the GUNNER profile is a blend of two of the best performing profiles of all time, Gov't and Pencil.
Proving that every once and awhile, the Government can do something right, the GUNNER's profile from the extension to the gas block mimics that delicious taper. From there, common sense takes over and the GUNNER moves to a .625" gas block journal and our famed pencil profile out front.
Removing the weight from the front of the barrel ensures maximum versatility and keeps material to the rear to maximize heat resistance and mitigate whip."
Barrel Material: 4150
Barrel Type: Button Rifled
Barrel Caliber: 5.56 NATO
Barrel Twist: 1:8
Barrel Length: 18"
Barrel Profile: GUNNER Light Hybrid
Barrel Gas System: Rifle Length
Inside Finish: QPQ Nitride
Outside Finish: QPQ Nitride
Muzzle Thread: 1/2-28 TPI (Threads Per Inch)
Gas Block Diameter: .625"
Gas Port Diameter: .081"
Barrel Extension: M4
Weight: 1.44 lbs
Magnetic Particle Inspected!
11-degree Target Crown