What’s the shortest mid length gas system for a ar15 that will run suppressed?

[nikdanja]

I shot my buddys mid length sbr suppressed the other day and it was really flat shooting compared to mine. (I have a 10.5 carbine system with an adjustable gas block. Yes it’s tuned right)

He has the A5 buffer system along with a mid length barrel that’s 13.5 I believe. The only thing I didn’t like was the OAL Of his rifle. He was saying that you have to watch out for how long your mid length barrel is because if it’s to short, it won’t feed.

So my question is, can I get a barrel that’s a mid length gas system and with a bigger gas port in the barrel? I was thinking I can still get a really short package, but still have reliable cycling.

Yes, I will be shooting my rifle suppressed. I also want this rifle to be reliable unsuppressed.

 

[TheNoviceVet]

Might take some tuning if you are doing it yourself, but triarc does a 12.5 mid and bexar does a 11.5. That’s about as short as you can just because of the length of the mid length tube.

Faxon 11.5" Gunner, 5.56 NATO, Mid-Length, 4150 QPQ

Bexar Arms (pronounced "Bear" Arms) is a small shop with the mission to give you our undivided attention so that we can tailor fit a solution to your individual requirements. For shooters, by shooters. We want to help you build the perfect AR for your unique needs.

www.bexararms.net

 

[iktomi]

If your running suppressed, you shouldn't have any trouble with an 11.5" midi (using pretty standard parts.)

Cant go too much shorter, as there isn't a whole lot of barrel left after the gas block for threading.

 

[TonyTheTiger]

and bexar does a 11.5.

Faxon 11.5" Gunner, 5.56 NATO, Mid-Length, 4150 QPQ

Bexar Arms (pronounced "Bear" Arms) is a small shop with the mission to give you our undivided attention so that we can tailor fit a solution to your individual requirements. For shooters, by shooters. We want to help you build the perfect AR for your unique needs.

www.bexararms.net

That's a Faxon barrel. Which is kind of a long way of saying a meh barrel.

 

[nikdanja]

Might take some tuning if you are doing it yourself, but triarc does a 12.5 mid and bexar does a 11.5. That’s about as short as you can just because of the length of the mid length tube.

Faxon 11.5" Gunner, 5.56 NATO, Mid-Length, 4150 QPQ

Bexar Arms (pronounced "Bear" Arms) is a small shop with the mission to give you our undivided attention so that we can tailor fit a solution to your individual requirements. For shooters, by shooters. We want to help you build the perfect AR for your unique needs.

www.bexararms.net

Do you have any experience with this?

 

[nikdanja]

If your running suppressed, you shouldn't have any trouble with an 11.5" midi (using pretty standard parts.)

Cant go too much shorter, as there isn't a whole lot of barrel left after the gas block for threading.

Do you think it will run reliably with the can off?

 

[TheNoviceVet]

Do you have any experience with this?

I have a triarc 12.5 that runs suppressed and Unsuppressed without issues. Bexar is a really responsive guy will answer any questions you have about his services and parts. But I have never used his 11.5 middy

 

[Evintos]

Do you think it will run reliably with the can off?

The following is what I remember from the top of my head - The Faxon 11.5" gunner midlength gas will run unsuppressed usually with an H2 buffer (like most if not all Faxon barrels) unsuppressed (depends on how gas efficient your BCG is). Since it has a ridiculously large 0.110" size gas port that was chosen to allow for end user adjustment for necessary gas flow volume with the reduced port pressure of a midlength system and shorter dwell time, an adjustable gas block is basically required. The barrel was designed primarily to address barrel length restrictions for some suppressors as well as reduce wear and tear on operating system components due to slower cyclic rate and lower port pressures with the 11.5 midlength.

Nathan of Faxon Firearms (I don't think he works there anymore) answered a bunch of questions about these barrels when they first came out. If you google these keywords "Nathan, Faxon, 11.5" I'm sure you'll find the discussion with all the info.

 

[just browsing]

I’ve built a couple uppers with the AR Performance 12.5” mid length barrels:

12.5" 223 Wylde 3R SBR/pistol barrel- 1/2-28

They are definitely flatter shooting than most any properly tuned carbine length gas system I’ve used, but I will say that they also definitely prefer to be shot with a suppressor. It’s not that you can’t get them to run without one, but at least in the case of the AR Performance barrels, the gas port was sized to be run with a can.

Regarding gas blocks, I started with an AGB, but I didn’t have much adjustment before it would short stroke so I was running it wide open anyway. I switched to a Badger TDX but honestly either or will work. I guess for me, it was more important to maintain solid reliability than the softest/flattest shooting gun possible. Also, just want to mention that ammo selection and suppressor (ie back pressure) will obviously play a significant role in how the gun performs too.

I do use Bootleg suppressed bolt carriers and the VLTOR A5 system so I have some tuneability built in… I can switch the carrier setting or buffer weight depending on suppressed vs. unsuppressed, type of ammo, conditions, etc. so there is some level of adjustment.

I know a lot of guys point to reliability being the concern about mid length shorties, but in all honestly my carbine uppers just seem over-gassed and snappy anymore. I guess if I had to grab one that’s going to run no matter what it would be the carbine, but the other 99% of the time I much prefer the mid.

 

[Badfinger]

I run a 10.5 barrel with fixed gas block and a 15 4.9 OZ Heavy Buffer without a problem and a 4.75 barrel in 300 Blackout. The .223 requires no tuning and the heavy buffer really smoothed it out, The Blackout required a little tweaking with the buffers and they both required multiple tax stamps.

 

[346ci]

Another 12.5" ARP user here, using a syrac gas block it runs great with or w/o the can.

 

[TheNoviceVet]

I’ve built a couple uppers with the AR Performance 12.5” mid length barrels:

12.5" 223 Wylde 3R SBR/pistol barrel- 1/2-28

They are definitely flatter shooting than most any properly tuned carbine length gas system I’ve used, but I will say that they also definitely prefer to be shot with a suppressor. It’s not that you can’t get them to run without one, but at least in the case of the AR Performance barrels, the gas port was sized to be run with a can.

Regarding gas blocks, I started with an AGB, but I didn’t have much adjustment before it would short stroke so I was running it wide open anyway. I switched to a Badger TDX but honestly either or will work. I guess for me, it was more important to maintain solid reliability than the softest/flattest shooting gun possible. Also, just want to mention that ammo selection and suppressor (ie back pressure) will obviously play a significant role in how the gun performs too.

I do use Bootleg suppressed bolt carriers and the VLTOR A5 system so I have some tuneability built in… I can switch the carrier setting or buffer weight depending on suppressed vs. unsuppressed, type of ammo, conditions, etc. so there is some level of adjustment.

I know a lot of guys point to reliability being the concern about mid length shorties, but in all honestly my carbine uppers just seem over-gassed and snappy anymore. I guess if I had to grab one that’s going to run no matter what it would be the carbine, but the other 99% of the time I much prefer the mid.

The bootleg adjustable and vltor makes my 12.5 mid so nice.
My only issue this far is it wont lock back on empty on underpowered ammo such as wolf (with a a5h1). It cycles fine

No issues on any military ball surplus.

 

[iktomi]

Do you think it will run reliably with the can off?

What does reliable mean?

200 rounds between cleanings?

2000?

I run high back pressure cans.

I tune to those, as a rule.

The shorter the dwell (distance between port and open venting post projectile leaving the unsuppressed muzzle) the more open the gas port to add enough energy to the reciprocating system.

Using standard parts, it is a bit trick to get the suppressed system to run pleasantly, and still have 'reliable' unsuppressed functions.

So I tune to suppressed. (I am not a savage.)