Which gas length for 12.5" barrel.

[loveha]

Currently waiting on a stamp (cashed 7/23, two more months?) to SBR a lower I just built. Also waiting on a stamp for a Sandman Ti but buying a Sandman S in a month.
Looking to build an upper for a 223/5.56 SBR with a 12.5" barrel. Just bought a Radian upper with 10" hand gaurd. The lower has a JP H2 SCS. The two barrels I'm looking at are either...
223 Criterion Hybrid which has a carbine length.
5.56 Triarc Track which has Mid Length.
Not going to be using an adjustable gas block on this.
Ammo most likely is going to mostly be 55gr Wolf Gold. (It's cheap and decent and goes pew pew.)
The big question is dwell time when not suppressed with the mid length. Will I have enough for a a regular weight BCG with an H2 buffer. I have a lightweight BCG from cryptic coatings to try that I have plans for in another build and the BCG from my DD 300Blk. But this gun I want to be reliable, and would rather not use the lightweight BCG. I'm leaning towards the Criterion barrel with the carbine gas system, just not sure.
So I guess what I'm asking is who has experience with one or both barrels and gas lengths.

 

[260shooter]

I run a Noveske 12.5" with carbine gas with no issues.

 

[loveha]

I run a Noveske 12.5" with carbine gas with no issues.

What weight buffer?
Not really expecting issues with carbine. May be a little over gassed when suppressed? Other than that things should run fine no matter what I throw at it.
Just wondering if I can get away with an H2 buffer with normal weight BCG with the mid length unsuppressed. If I have issues, guess I could get a regular JP SCS to swap out if I'm not running suppressed? Didn't bother with getting the buffer retaining pin for the lower, so swapping that out should be no issue.

I'm most likely over thinking this, but doesn't hurt to ask.

 

[RyanScott]

Carbine unless it’s 100% suppressed. .063” port.

 

[loveha]

Carbine unless it’s 100% suppressed. .063” port.

That's what I figured and most likely picking up. However gas port size, no idea on what it is on Criterion barrels.
Then I started doing some googling and discovered that companies treat their gas port sizes like some damn secretive voodoo magic. I'm sure it will be just fine either way.

 

[Snuby642]

You can change buffers in a minute, you can change the weights in one in 5.
Mix match and color code till you get it running good.
All cheaper than an adjustable. Whole thing will run better, softer than stock.
Check the web for tungsten weights, get a 3 pack and play.
I have 2 tungsten in several different length uppers but all depends on round preferences.
Many good threads / vidios on the subject.

Not using a buffer retaining pin? Why , you can just push it down while changing buffers.
I do not recomend not having one installed!

 

[brcook03]

I don't have direct experience with those specific barrels but I do run a 12.5" barrel with carbine gas system and a .065" gas port. My lower has an VLTOR A5 system with their A5H2 buffer and I run a Tubbs AR-10 flatwire spring. Zero function issues suppressed or unsuppressed. No gas blowback with a Sandman-K can and a little bit with a Saker 556 can (but not bad).

 

[loveha]

Not using a buffer retaining pin? Why , you can just push it down while changing buffers.
I do not recomend not having one installed!

Lower I am awaiting my stamp for has a JP Silent Capture Spring. It's not needed.

 

[CJS-6.5]

That's what I figured and most likely picking up. However gas port size, no idea on what it is on Criterion barrels.
Then I started doing some googling and discovered that companies treat their gas port sizes like some damn secretive voodoo magic. I'm sure it will be just fine either way.

Most start a little small. Just pop it off and go up in small increments. Common sense goes a long way. If over gassed then monkey with the buffer. Or reload to suit the gun.