Meh, 16 to 14.5 would probably work okay


Found this old thread

Haven’t waded through ithttps://www.ar15.com/forums/armory/Aug-SBR-/43-497465/

Isn't your 16" AUG already the same length as your 10.5" AR?

Just my two cents, if you're dead set on cutting it down, at least have a suppressor on hand.

No, seriously. If you can't get it to work unsuppressed by opening up the gas port, adding a can would increase the dwell time and up the backpressure enough to get it working. Then you'd just have to figure out tuning the gas vent size to balance reliability with cyclic rate.

Pursuitss, if you already went down a similar path and ended up with poor results then wouldn’t that be forewarning that you run the risk of the same outcome?

Maybe you get it working just right and there’s no issues but I can’t help but think the likelihood of it not working out is more probable than not.

@pursuitss

You're making a horrible mistake, don;t do it.

BTW, cutting down a 16 to a 14.5 is bad enough going from a 20 to a 16 or a 14.5 would be be even worse.

Best wishes.

Steyr did make a 14" "Commando" barrel...they pop up on gunbroker now and again, but be prepared to pay. I bought two, sold one a few years ago, and am hanging onto the other..

@Evil_Ed

Can I ask what they went for and when?  I happen to have one and have been considering putting it up on GB.  Considering the insane rarity I've been having a hard time getting any info.  I think I saw somewhere that PJ's brought in about 80 of them way back when.

Forget them, you should DO IT!... but don’t enlarge the gas port to get it to run, instead reduce the outlet port in the gas valve (or possibly remove the piston rings or fab a new piston and reduce the port further). That would be awesome dedicated suppressed. I don’t understand why they chose to use so much gas and vent the excess versus using less and venting less or none.

@Manticore_Arms have you confirmed this personally regarding the angled port? My memory is fading, but I want to say I checked my factory 14 when I had it and it was not angled.

I got two from Pete way back when...I want to say the price was around 700 each? Maybe a little less? It was a long time ago, like 2003 or so when I bought them.

When I sold my green one in 2011, it went for just about 1300 on Gunbroker..

I have a factory 16" barrel that was cut to 14" and I brought it back up to 16"+ via a permanently attached custom flash hider.  The back half of the flash hider is a AAC 51th and the front half is an OEM Steyr Tulip.

In my experience you don't need to open the gas port in the barrel or modify the port in the gas block that allows gas from the barrel into the piston expansion chamber.  The actual gas port hole in the barrel and gas block leading into the piston expansion chamber has more than enough volume to run the gun with ~2" removed from the barrel.

However you are going to be in store for tuning the bleed off orifice(s) in the gas block plug.  

Essentially you are going to need access to a TIG welder to weld the existing port(s) closed, a very tiny end mills (or two), and small collection of small wire sized drill bits to slowly open up the new hole(s) in the now welded closed gas plug.  Its been a couple of years but if I remember correctly that gas plug material is hard as hell (even after welding the ports closed) and I needed to use a 1/32nd or 1/6th carbide endmill to drill the first pass on the new vent holes.  Once the carbide end mill punched the initial new hole, I could use regular jobber drill bits to progressively open the new vent holes from there to tune it as it will be way over gassed with the vent port completely welded shut   The port holes are tiny so make sure you go super slow and use plenty of lubricant so you don't snap an endmill or drill bit off in your gas plug.  

One thing to keep in mind is that unlike tuning a short AR barrel, you are not drilling to allow more gas into the system, you are drilling to allow more gas to escape the system.  On an AR you drill, test fire, drill test fire, etc. until the gun can lock back.  With an AUG you are starting from an over-gassed position and reducing the energy into the piston with each progressively larger drill bit.  So at some point you will go from functioning to non functioning once you take a step too far.

I ended up welding and redrilling two ports, one for unsuppressed use and another tuned for an AAC M42000.   The first hole when it finally got "over drilled" and the gun no longer cycled I made note of what drill size that happened at and then that vent hole became my new suppressed setting as it would then function with the increased backpressure from the suppressor.  I did continue to open up the now new suppressed vent hole as I knew it would run suppressed with the normal gas port vent size from previous testing before welding any of the ports shut.  

I then redrilled a new second non-suppressed gas port vent hole using what I had learned from the first (now suppressed) vent hole and stopped drilling at the proper hole size before it became to big.

One thing to keep in mind that nobody has mentioned is that with the shorter barrel and unsuppressed, your forward hand will get really peppered with blast.  Without gloves on  its not super pleasant to shoot with the front of your bare knuckles almost directly under the rear of the flash hider vents.

One last point if this is planned to be a non-SBR is you need to keep track of both the barrel length as well as the overall length.   On the AUG you can get the barrel to just a smidge over 16" and be legal at the barrel length but the overall length of the firearm will still be under 26".  I think I ended up with the barrel and hider right at 16-3/8th" to make sure I kept everything legal in term of OAL.  If you cut the barrel and repin to 16.01" the OAL will be too short.

I had read the same stories that it can't be done, etc.  but my barrel works  fine.   I also have a machinegun hammerpack so not only did I want to get it to cycle but I also didn't want it overgassed so the cyclic rate would stay reasonable as well and I didn't end up with bolt bounce issues, etc.   All that said, I honestly prefer the longer 16" barrels for normal shooting and the AUG isn't the best suppressor host either but it was an interesting project and does keep the length down a bit for suppressor use.

Hope this helps.

I have an MSAR with a cut down barrel that is 16.1" with a pinned and welded Noveske Pig.  It took some messing around with the gas port but it runs well.

Oof, that's a compelling argument for putting my black one on Gunbroker

So this is going to throw confusion into the discussion. It’s a point of ambiguity I’ve known for a while but I can’t confirm one way or the other.  

First, I do not have a 14”, technically 13.8” AUG barrel (just as the 16” barrels are technically 16.5” long with FH removed) even though I REALLY want one. I have almost everything AUG ownable but that darn barrel, carry handle rings, and the Australian optic. I even have things most don’t know exist or have never seen before, but that barrel is my unicorn.

That said, if I had one, I would absolutely put a carburetor jet cleaner into the port to gauge the angle (if any).

Why do I have doubts? Because a couple years ago I was speaking with Pete Athens who has forgotten more than I will ever know. On the angled port question he said that they are not angled. This conflicts directly with the graphic posted on his website, that he put there many years ago.

That leaves us in the odd position of the port most likely being angled because there is documentation stating so, however it is also likely unreliable because the one person who would know affirmed to the negative.

Who wants to sell me their barrel?

I can dig my barrel out and pop out the gas piston and check...what's a carburator jet cleaning tool

I don't think I have any pipe cleaners, but I can clear the cotton off a q-tip easy enough and see if the stick bends to more (or less) than 90?

Ok so I took a 20" barrel (recent manufacture, post-2010 I think) and my 14" commando barrel from early 2ks - using a small hex key, I was able to put the short end into the hole in the gas block and watch the end of it poke out into the bore on the 20" barrel.

On the 14" barrel, it was blocked/stopped short; I could not make it protrude into the bore at all. I couldn't also bend it to get it to go in; the key was too long on the long side to allow that much angle.

So...on my 20" barrel, the gas port from the barrel into the gas block looks to be 90 degrees; on my 14" barrel, it seems to be angled.

Evil_Ed,

Can you insert the long part of the hex key directly into the port and the bore from the front of the gas cylinder?  

I have no skin in the game, but it's interesting research none the less.

Photos are crappy so I apologize in advance...here's the 20" barrel, I'm able to poke the key all the way through:



Here's the 14...I'm holding the key the same way; pushing on it with my thumb; no va:

I can't tell from the photo, but if the key is entering the bore, then you must have put it in through the exhaust hole.

Can you get to the bore through the gas port while coming in from the open front end of the cylinder?  Edit:  (On the 14")

I don't know if this is even possible or not, but I can touch the port on my 20", coming in from from the open front end of the cylinder and the resulting angle looks to be about 45 degrees.

Yes, that was how I did it the first time, same result. I need to use the short end of the key to do it. I can see it protrude into the bore on the 20" (like I posted a few posts above, before I posted photos). It does NOT protrude into the bore when trying it on a 14".

Sorry, but let me confirm this in a way I can understand.

With your 14":

You can not insert the long end of the key into the bore via the exhaust hole in the cylinder like you can on a 20".

You also can not insert the tool into the bore through the gas port when coming in from the open front of the cylinder like the photo below, right?  The tip of that torx key is resting in the gas port.  It looks like a 45* angle to be which would be correct for a 14.

Correct, it will not go in at any angle that I can push it in, I don't have anything that is short enough to make it into the bore no matter what angle.

The point is: The same tool will for sure go into the bore on a 20" barrel; the gas port appears to be at 90/straight through from the barrel to the gas block.

The same tool will NOT enter the bore on a 14"; it stops early, as if the gas port is at an angle going into the gas block. The tool I have does not have the flexibility to allow it to enter and find what angle the port is at, but it is not a 90/straight port through, like the 20" barrel.

Thanks for confirming.  It all makes sense now.

I guess logically the port in the actual barrel should be at a 90, or else it would be oblong.  They probably drilled the barrel hole at a correct 90*, only a few mm rearward, and drilled the cylinder hole back at an angle to intersect the new location.  

That's my theory anyway, and explains why a tool stops where the passage changes angles.

Maybe check it with a wire?

Again, my memory is awful, but I thought I confirmed it was not angled on my factory 14" and even posted the results here. So, I looked for my old post, couldn't find it, but it seems many other are posting the "angled port" is incorrect as well...

Kent from TPD USA

Someone else here (I can't see who), post #17

I just took some pictures with one of those quasi bore cam things (mine is actually for checking ears, thanks Walmart )...you can see through to the chrome lining of the bore on the 20"; you CANNOT see straight through to the bore, no matter what angle I tried it with, on the 14". The ports themselves on the inside and outside of the barrel might be flat/circles, but it's not a straight through hole.

This crudely illustrates what I'm thinking.  14" barrel shown on the right.  

I'm not sure what order AUG barrel machine steps are done, but obviously this way they couldn't have drilled the barrel port with the gas block installed.  Just pure speculation on an interesting topic.

Barrels were banned for import under the Bush presidency (2005 I think). Steyr recently imported the 9mm barrels in so called “sporter” configuration (no threads), but ATF didn’t allow further importation. If there was another attempt to import further AUG barrels, they’d have to do them without threads as in the AUG Z. Other companies import barrels, so Steyr should be able to do so legally (otherwise they would be treated arbitrarily). My guess is that someone wasn’t anal in ensuring the paperwork was submitted properly and/or they gave up after being denied.

Right before covid I had a conversation with the new head of Steyr’s US operation. He said they were testing a 14” barrel that only runs on quality brass ammo. Last year I tried to follow up with him and heard nothing back. I can check with others over there who might know more. Will update here if I get a response.

The carburetor jet cleaning tool is just a collection of tiny varying diameter wires that are ribbed to aid in reaming carb jets of fouling. They are flexible and made of a soft metal, so it won’t damage the barrel and they’d flex into the path of the gas port.

Unfortunately the BATFE currently considers AUG barrels to be "non-sporting" so they are ineligible for importation to the US for consumer sales.

While I didn't have a conversation with him directly about 14" barrels, this is what also killed the importation of the 9MM conversion kits.  Initially the barrels were considered non-sporting since they were 16" long and not threaded, somewhere along the lines after the kits were imported somebody decided that even the neutered 9mm barrels were non-sporting and no more could be brought in.

This is why Steyr USA has to have the current AUG barrels made in the US as well as the receiver casting machined here as well as those two parts (barrel and receiver) cannot be imported.

I asked about just getting the barrels done in the US and he said the cost and minimum order quantity would be too high to justify bringing in barrel-less kits and then having barrels made in the US to complete them.

The only way I could see 14" Austrian barrels brought in is if Steyr could come up with some sort of legal AUG style "pistol" that would meet the points requirement to be legal for importation and that had a 14" barrel which could be harvested off the imported pistol.   Similar to how short AK barrels come in via Draco style pistols, but can't be imported as raw uninstalled barrels.

The best and most realistic option would be for Steyr USA to contract with FN or one of their other barrel manufacturing partners and have a run of 14" barrels made here in the US using original Steyr Austria blueprints.   However, Steyr USA has never really seemed interested in making barrel in much of any length but 16" with a few handful of exceptions.

You are correct, non-sporting barrels and receivers were brought in up until 2005 as "repair" barrel and receivers.  This is how those stripped Austrian AUG receivers came into the Country in the early aughts as well.

The BATFE took a position change to disallow importation of repair barrels and receivers.  Even dual use barrels where they could be used on sporting or non-sporting firearms were dis-allowed.  i.e. a Romanian WASR barrel that is a replacement barrel for a sporting single stack Romanian WASR AK pattern rifle can't be brought in raw because it can use used in a non-Sporting dual stack mag AK.

My impression is that all the current "foreign" non-sporting barrels that come into the Country are brought in "unfinished" and completed in the US, although I had heard that the ATF may have become more open to importation of dual sporting/non-sporting use barrels.

https://www.atf.gov/file/84901/download

Somewhat related, is there anything special about this AUG 16" chrome lined barrel?  https://www.gunbroker.com/item/937472989

I've got an unfired AUG in the closet with a chrome barrel.  If they really are something special, I'll put it up on the chopping block.  

It's a 1/7" barrel twist; IIRC they didn't bring in too many of those. Most are 1/9" IIRC..

Bring in from where?  it says USA on it.

Sorry, I meant didn't make many available in the US. I always assumed they were imported but as we can see above...I guess not

Pete at PJs was working with Steyr on a US made 14” barrel several years ago. If I recall correctly, it was going to have a integral muzzle device to bring it to 16”. It never went anywhere.

Is that separate from being a chrome lined barrel?  Mine are chrome lined and look like the one in that auction except I dont see that "7" rollmark on them.

Yes, IIRC all the Steyr barrels are or at least were chrome lined; that's not the rare part. The rare part is the 1/7" twist.

Yes, there were only 2 production runs of 1/7 barrels in the US. (Both by FN).
They were sold on complete AUG A3 carbines and also as spare barrels.

The first run was marked with a 7 (as seen in the above GunBroker auction) and the second run had no special marking to indicate twist.

The rest of the barrels are 1/9.
When Steyr stopped sourcing US barrels through FN, there were no more chrome lined barrels for US production.

I found an old thread saying the second run had date stamp 1701.  Mine are stamped 1401 and 1501, so there goes my winning lotto ticket.

My 20" is stamped 1602. Darn