Rifle length barrel coversion

[Jacobpoirier]

Hey everyone,
I'm looking at getting an 18" barrel for my AR.
I've got a JP silent capture spring which eliminates the need for a rifle buffer. I also already have an adjustable low pro gas block. My question is this: would I only need a rifle length gas tube (as well as a new rifle length barrel obviously) to complete the conversion? If so, why wouldn't I? Or am I completely offside here?

 

[hbean]

It is your money have at it!

 

[cadgo]

You should be good to go. I can run my 18inch upper on my rifle or carbine lower with 100% reliability. For the most part the gas system and buffer system are independent.

 

[Magoo22]

When you say 100% reliability on the 18"upper what length is the other upper you have? What ammo are you shooting? I am curious because I have an 11.5" that was bought with the lower and when I put my 18" on I can't shoot 55gr ammo. Tried PMC and some hand loads with 3031. 77gr with Varget or N540 runs flawlessly. Not 100% sure but I read a few things that say there is not enough gas pressure in the ammo to cycle the bolt due to longer gas block placement. Could try a softer spring but that might cause over gassing the short upper. New to this so just curious on what to expect. I would like to switch back and forth with 100% reliability as well.

 

[Leg]

It depends on the barrel. 18" are available with mid length and rifle length gas tubes.

I've been toying with the idea of a Faxon Gunnar 18" myself as a kind of jack of all trades build.