Gas Tube Length

[cobra655]

Ok i am building a DMR type rifle for my next AR15. I already have the lower done. Mega Billet ambi lower with SOLGW parts kit and Larue MBT-2S trigger. I have a Vltor A5 receiver extension with and A5H2 buffer in it and stock Vltor spring. I will be using an 18" stainless Deadshot barrel. My question is related to gas tube length. In the past I have always just used a rifle length gas system and have been pretty pleased with the results. recently it was brought to my attention that maybe I should be running a mid-length system instead. What is everyone's opinion? I don't intend to shoot lighter than 55gr and mostly 62 to 77gr. The rifles purpose would be varmint hunting/prairie dogs and the occasional rifle competition.

 

[Kadams1563]

If you already have the barrel then your gas tube length is already decided by the barrel.

18” I would use rifle length.

 

[cobra655]

If you already have the barrel then your gas tube length is already decided by the barrel.

18” I would use rifle length.

I don't have the barrel yet.

 

[Shooter McGavin]

For an 18” barrel go rifle length. If you were using a 14.5 I would say mid length over carbine length. The reason everyone is doing that with shorter barrels is to get less recoil.