12.5 midlenth gas port size?

[JoeBobJoe]

I was wondering if there are standard gas port sizes for midlenth gas system 12.5 ( pistol) barrel chambered in .223/5.56?
Thanks.

[Wake27]

Nope.


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[titsonritz]

Nope 2nd.

[bamashooter]

You can scroll through the included link and get an idea by assorted brand names and source of measurements.

https://docs.google.com/spreadsheets/d/1tXunBDX5Gaz87BqxwNxDUlWNK9nEv-cZEQoLq2JXXrk/edit#gid=766121382

[Five_Point_Five_Six]

You can scroll through the included link and get an idea by assorted brand names and source of measurements.

https://docs.google.com/spreadsheets/d/1tXunBDX5Gaz87BqxwNxDUlWNK9nEv-cZEQoLq2JXXrk/edit#gid=766121382

Maybe I missed it but I didn't see a single 12.5 mid length on that whole list.

[constructor]

I was wondering if there are standard gas port sizes for midlenth gas system 12.5 ( pistol) barrel chambered in .223/5.56?
Thanks.

Probably only 3 companies making midgas 12.5s.
We use .081"

[Robb Jensen]

I did mine at .080”, it’s a bit stout. I’d suggest starting at .075” and working up until it works with the ammo you use.

[JoeBobJoe]

Thanks for the info, I kind of stumbled on the 12.5 midlenth by accident.
I saw a few midlenth pistols builds on line & it intrigued me. I got a over gassed midlenth barrel sitting around.

[JoeBobJoe]

I did mine at .080”, it’s a bit stout. I’d suggest starting at .075” and working up until it works with the ammo you use.

Ok. That .075 is about average on a midlenth 16.
Thought it be about.085 or more.
Good to know.

[bamashooter]

Maybe I missed it but I didn't see a single 12.5 mid length on that whole list.

Perhaps so. Didn't scrub the DB. Back to the question. There is no standard.

[Wake27]

There’s not even much of a standard for 12.5 carbine, I think too few brands use the 12.5 for there to be a large sample to draw from.


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[Five_Point_Five_Six]

My next upper project is going to be a 12.5 mid FSB setup to run suppressed full time. I haven't yet worked out how I'm going to do it, but I'll probably buy a 16" mid length barrel from a reputable manufacturer and have D Wilson MFG chop it, then see how it runs and adjust the gas with a BRT EZTune gas tube if needed.

[JoeBobJoe]

My next upper project is going to be a 12.5 mid FSB setup to run suppressed full time. I haven't yet worked out how I'm going to do it, but I'll probably buy a 16" mid length barrel from a reputable manufacturer and have D Wilson MFG chop it, then see how it runs and adjust the gas with a BRT EZTune gas tube if needed.

If anything you may need to open up the gas port on a midlenth 16, I doubt you'll have to try to tighten it with a BRT tube or adjustable gas block. Check gas port size before you buy it. I'm thinking.075 ish will be average for a 16 midlenth. Shortening the barrel usually means opening up gas port to make up loss pressure especially if dwell time is shorter, like on a midlenth.

[MJinPA]

I had my 16” white oak barrel cut to 13”. When it was cut the gas port was measured at .076. Had about 8k down the pipe prior to cutting.

Initially it was finicky. Has been 100% reliable (with and without a can) for about 5k rounds after moving to an A5 buffer setup with vltor h2 buffer and Geissele rifle spring. Without the can and a yhm 3 port brake it also has near zero recoil although loud as hell.


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[Rayrevolver]

Have you guys considered this barrel below? Can't do an FSB though. I was trying to find a Triarc 12.5 mid but ended up with this 12.5 EXC BRT in a mini-recce... that I never shoot.

https://blackrivertactical.com/WP/BRT-12-5-OPTIMUM-Hammer-Forged-Chrome-Lined-Barrel-p258933205

https://live.staticflickr.com/65535/52215870669_5489834093_c.jpg (https://www.flickr.com/gp/151953216@N05/ZL7p4613wr)

[Five_Point_Five_Six]

If anything you may need to open up the gas port on a midlenth 16, I doubt you'll have to try to tighten it with a BRT tube or adjustable gas block. Check gas port size before you buy it. I'm thinking.075 ish will be average for a 16 midlenth. Shortening the barrel usually means opening up gas port to make up loss pressure especially if dwell time is shorter, like on a midlenth.

I doubt it will need to be opened up to run suppressed.


Have you guys considered this barrel below? Can't do an FSB though. I was trying to find a Triarc 12.5 mid but ended up with this 12.5 EXC BRT in a mini-recce... that I never shoot.

https://blackrivertactical.com/WP/BRT-12-5-OPTIMUM-Hammer-Forged-Chrome-Lined-Barrel-p258933205

https://live.staticflickr.com/65535/52215870669_5489834093_c.jpg (https://www.flickr.com/gp/151953216@N05/ZL7p4613wr)

Probably a great barrel just not what I'm looking for.

[JoeBobJoe]

I never ran a suppressor, but makes sense you'll be adding what you cut off then some to barrel length. Makes sense not have to open port size.
I doubt you'll have to worry about it being over gassed.

[Todd.K]

I doubt it will need to be opened up to run suppressed.

You can definitely reduce the gas for suppressed only. It will make a very smooth shooter if you do.