Gas Port Size; 12.5” Mid-Length 100% Suppressed

[maximusdecimusmeridius]

I have an LWRC DI with a 16” mid-length barrel. It is being cut down to 12.8” by the gunsmith. I used a gauge pin and the gas port seems to be .78” currently.

It will be used 100% suppressed. Will use an H3 Buffer. Will only use 77 tmk hand loads.

There are companies that sell gas tubes or gas port inserts to restrict gas

I am thinking the equivalent reduction that a .62 gas port would have would be appropriate for the above

 

[mavrick]

Black River tactical tube might work. I know they make them for the LMT MWS but not sure about the standard AR15 tube.

 

[maximusdecimusmeridius]

Yes. That is one option.

Here is a chart for reference about port sizes

 

[dogman]

Black River makes tubes for standard ARs.

 

[maximusdecimusmeridius]

Black River tactical tube might work. I know they make them for the LMT MWS but not sure about the standard AR15 tube.

Yes. It would work. I would rather spec the size than them though https://blackrivertactical.com/WP/BRT-EZTUNE-Gas-Tube-Configurable-Midlength-p103167236

 

[PBWalsh]

The BRT gas tubes are phenomenal. Get the custom one and specify your barrel in the drop down options. Its worth the price. I have had three; one on a mid-length Triarc 11.5”, Rosco mid-length 16”, and BRTs own optimum (intermediate)16” barrel.

 

[maximusdecimusmeridius]

I will also be ordering a brt gas tube for a 10.5” LWRC di with carbine length gas system.

Will probably spec .55” for the tube on that one

 

[Clayman]

BRT or adjustable gas block imo

 

[maximusdecimusmeridius]

I really like the LWRC gas block and want to keep it if possible

Would prefer just changing the tube

 

[msgriff]

RCA adjustable gas key, properly installed.

ETA: There is also the DIY version of the BRT CustomTune, which they no longer sell.

 

[maximusdecimusmeridius]

I’m a huge LWRC fan boy and I really like the design of the gas key and carrier being one piece on the lwrc’s

 

[msgriff]

Depending on the suppressor, a 0.78" port on a 12.8" MLGS barrel might not even be undersized. The shorter the dwell, the larger the port.

 

[maximusdecimusmeridius]

It will be a TBAC dominus sr so it will have some back pressure but I will also be using an h3 buffer. Just trying to limit the gas as much as I can for high volume suppresses shooting

 

[CaptArab]

The BRT folks do this all day, they'll pick a good one for you and if you're not happy they'll swap it out.

 

[021411]

I have a 12.5 mid length Rosco that gauged out to 0.078” on the port. I got a BRT tube for it for 100% suppressed using an A5H0 buffer. They sent me a 0.067” tube. It shoots soft af now.

 

[Cascade Hemi]

A .060" port would probably cycle the gun with M193 or M855 in your current configuration. YHM has .063" gas blocks. BRT gas tubes have a relatively short service life and the harder you push the gun the shorter it gets. The YHM gas block has .170" of material thickness whereas the BRT has something close to .045" thickness.

Suppressor Gas Block Assy (.750")

This .750" gas block is designed to be used exclusively with suppressed rifles to reduce blowback and enhance the shooting experience. Visit to learn more!

yhm.net

 

[tucaz]

i just went round and round with some barrels with large ports for dedicated suppressed

i had a 16” fn mid cut down to 12.5 with its .076 port and it was way too big. the .067 BTR tube made it perfect.

i also use an .067 BRT on a 16” mid with a aac m4-2k can and that made it much softer and easier to stay in the glass (scoped rifle)

i’ll be getting another BRT tube for an 11.5” centurion with a .069 port that is too big with my particular suppressor. it out runs the mags. probably get both an .065 and .0635

i was kinda shocked the .069 wasn’t small enough.