OK, I've posted this in the bullpup website, but maybe there are some additional folks here with some ideas on how to do this.

As we know, the AUG product improvement team is about as aggressive as the Steyr marketing team - meaning the likelihood of them getting on the ball in our lifetimes with popular 5.56 action alternate cartridges, is about zero.  

So, knowing that, I have access to a machine shop with match grade barrel machinists, who've already said it'd be fun to do an AUG BBL for fun, if I provide the materials.  I was looking at doing a match .223 barrel, but I got to thinking - screw that, why not give the AUG a power upgrade?  I'm sure this has been hashed around before, so links to other thread that I might have missed on this, would be welcome.

So, I can get and cut a barrel to pretty much anything I want, that will fit into an AUG.  Thing is - I see 4 remaining challenges.

1) How can I get my hands on a gas system to mount to the BBL?  And how do I mount it to, said barrel?   Someone said it's heated and compression fitted in some way - is that right?  That sounds like a real challenge of getting, and adding, if so.
2) The AUG BBL does not thicken in the chamber area.  If I cut something like 6.5Grendel (or 6.8 - not here to start a pissing match on that), will the chamber wall be strong enough?  
3) I'm guessing I'll have to machine a matching bolt?  I'm sure I can cut it, but there's more to a bolt than cutting it, as I think there are metallurgical strengthening steps involved.  I suppose I could try to use a cartridge that has the same case body size as .223, and so use a factory bolt, but my interest fades fast if so, since the point of 6.5 is to have a thicker body, so that it can hold a lot more powder to push that bigger bullet.
4) The steel receiver insert (I don't know what it's called), into which the barrel and the bolt lock, is sized to a certain dimension and strength.  Would I need to machine a different one of those too?  And even if I were able to use an old one as-is, are those lugs strong enough to handle something like 6.5 Grendel?

As a bonus, has anyone every tried loading 6.5 grendel rounds (or 6.8) into an AUG factory mag to see if they even fit?

I'm wondering if this project is more trouble than it's worth, with too many notable challenges (and costs)?  Has anyone gone down this path?

Ironic username is ironic.
But seriously, questions 2-4 are engineering problems.
Are you willing to consider a less-challenging caliber conversion?
Seems like .300 Blackout would be a slam-dunk, if you can solve #1.
Case dimensions and OAL should be compatible with factory mags.
No need to redesign the barrel lockup or bolt.
Gas port size may take some trial and error.

<-- short bus engineer (civil).  Dynamics be hard, yo.

lazyengineer,  

Check out this old Thread on the subject:  https://www.ar15.com/archive/topic.html?b=6&f=43&t=379098    

I personally think a 6.5mm Grendel-chambered AUG would be a super combo. Good luck!                  

Like I wrote on the other forum, I know someone with 10 gas blocks for the AUG. Although he wouldn't sell to me in the past, I'd still like to pester him as I have my own ideas for what to do should one come into my possession.

It would look like crap, but I guess if it were a worst case scenario, you could pin it in place like you would on other rifles.

6.8 SPC has been done in the MSAR, I don't think 6.5 is possible.

The receiver insert is the trunnion. I wouldn't mess with trying to make a new or modified trunnion, there's not much room to begin with... The only trunnions that are worth anything are Steyr trunnions, potential problems from all the rest.


*enlarged to show detail

lets do 6.8 then. the longer OAL of steyr mags+20" barrel would be great.

A 6x45 or 25x45 would be a lot easier and allow heavier bullets with more frontal area.
6mm bullets are less expensive and will make impressive results on hogs and deer.
The monolithic copper ones work very well.

This thread has my interest.

I remember in the lead up to the A3, Steyr had literature out saying that there was going to be a 6.8 version.