Chipped AUG trunnion?

[briansmithwins]

Found this bright shiny spot on the trunnion last time I cleaned the AUG (A3 model, serial 6USAxxx). I don't remember the scallop being there...

I didn't find any extra metal pieces floating around but I'm probably not going to shoot the rifle until I hear back from Steyr USA.









BSW

 

[HOOfan_1]

How does the bolt look? What could damage that area other than the bolt?

 

[barnbwt]

Sure looks like it, simply going off of the apparently sharp corners. I wonder what could have cause that? It's not like the back of the lug sees anything particularly interesting, stress or shock wise, even during feeding. Is there a matching contact on the bolt carrier? I have no idea what stops the carrier in the AUG, aside from, I'm guessing, the worn spots over the breech area. If the carrier was banging harder on that one little corner I could maybe see an issue

Let us know how Steyr treats you

TCB

 

[briansmithwins]

I'm thinking there was a small defect in the trunnion that weakened that area and it finally failed. I agree that it's not really a highly stressed area but, the rear trunnion is going to be a pretty highly stressed part that sees repeated shock loads. I didn't see any damage to the bolt but I didn't look closely either.

I figure I could keep shooting the rifle for a long time with no problems, but why?

BSW

 

[briansmithwins]

Update: Sending the receiver and recoiling parts back to Steyr today. I'll update this post when I get it back.

I did look at the bolt closer last night before I packaged it up. There was no damage at all to the bolt. The rifle has less than 1000 rounds thru it and has literally never* malfunctioned.

BSW

*I did manage to get some FTFeed but that was using the NATO stock, STANAG mags, and JHPs that have trouble feeding in other rifles too.

 

[boricua9mm]

Steyr will take good care of you. They'll probably call you to tell you what happened and what the repair is, and they'll probably send you a mag to make up for the shipping. They did that for me when I had to send my receiver in for a bent receiver plate. Let us know how it goes.

 

[briansmithwins]

They did that for me when I had to send my receiver in for a bent receiver plate. Let us know how it goes.

Just curious, how'd you bend the receiver plate?

BSW

 

[boricua9mm]

Oversized charging handle nipple, out of spec charging handle bushing, improperly heat treated receiver plate, or all three. They simply replaced all of those items at the front end of the receiver.

An Austrian fellow called me to explain the repairs; that was reassuring!

In this pic you can see the bushing walking out and the bend in the plate.