What length gas system for a 18" AR15?

[Timradcliffe345]

What is the ideal length of the gas system for a 18" barrelled AR15 (for optimal function)?

Thanks.

 

[Timradcliffe345]

Obviously, the choice will be between the mid length and rifle length gas system. Question is which one?

 

[Z-Michigan]

Mid length gas system, definitely. And I don't know if rifle length is the 2nd choice - not sure it would be reliable with so little barrel after the gas port. AR's need a lot of tapped gas to work. The "dissipator" models sold by Bushmaster and others have carbine length gas ports, not rifle length. I suspect the 2nd choice on an 18" barrel would be the carbine (M4) length gas port, but definitely the mid-length would be better.

 

[Soybomb]

I've only heard good things about 18" rifle systems.

 

[waterhouse]

I've got one of each and I'm happy with both, although I've only had the midlength for about 6 months, so I haven't put a lot of rounds downrange with it yet. I have read (on the internet) that the rifle length may have trouble in cold weather. I have yet to take it anywhere cold enough to test this, but I've also read that Zak took his 17" gun with a rifle system to a cold match and it ran fine, so I'm not overly concerned.

If I could only keep 1 (eventually I'll sell them both) I'd go with the rifle length.

 

[Hoppy590]

midlength. some of the reading iv come across suggest rifle length doesn't have pressure for long enough.

 

[taliv]

rifle works absolutely fine and is the preferred length for 18" barrels. there's no reason to use mid-length.

 

[Timradcliffe345]

What is the distance from the muzzle to the gas block on an 18" barrel with:

1) Mid length gas system

2) Rifle length gas system

Thanks.