I've had this AUG A3 M1 for a bit now, round count is somewhere between 500 and 1000. The gun has always operated fine, except the bolt would fail to lock back after the last round maybe 1 out of 3 times. This would happen with Steyr and Magpul mags. Ammo used is milspec brass case M855, M193 and Wolf Gold, no steel case.

For the past couple hundred rounds I used the adverse gas setting, thinking it just needed breaking in. It seemed to work and I can't recall any instances of the bolt not locking back. Fast forward to today and I turn the gas back down to normal and hit the range. The bolt failed to lock back on 2 out of 3 mags.

I get home and strip the rifle down. I check the normal stuff. Piston has all gas rings, trigger pack is properly installed, rifle is clean, etc, etc. Then I notice the plate that locks up against the barrel seems to be getting hammered on and pushed out?

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Not really sure what the issue is here and if this related to the bolt not locking back. Any of you guys seen this before? Probably going to send some pics to Steyr and I would imagine they will want me to send it in. Bummer, I hate getting a lemon!

I see two problems in that picture. This is a problem that rarely affects some guns, but it is known. Call Steyr.

The sleeve on the side that is pushed up may be pushing on the plate with the 2 screws.  Did you disassemble?  Wonder if they just didn't press that sleeve in to be flush or maybe the the plate is supposed to retain the sleeve and it is too long.  Mine is flat and not pushed up.  It is Austrian.

Could you elaborate? So I can better explain the problems when speaking with Steyr.

The receiver front plate is bent toward the charging handle side of the gun and the charging handle side steel bushing on the front of the receiver is pushed out.

They'll know exactly what you're talking about.

To the question of the failure of the bolt locking back, I'd say it's unrelated.

Thank you for the help, I`ll update this thread with what happens.

Talked with Herbert at Steyr about the issues with the rifle, nice guy. Going to send the rifle in next week for repair.

Keep us posted.

Late to the party, but I believe you are looking at two separate, unrelated issues. AUGs have stoopid strong springs when new. My usual recommendation on a new AUG is to store the gun with the bolt locked to the rear for at least two weeks to help the springs take their initial set. The spring tension may very well be the cause of your short strokes.

I had the same issue with the bent receiver plate on my old A3; I had to send it in as well. Honestly, I've had to send both my A3 and M1 back, but that's another discussion. The issue with the bent receiver plate is that either the heat treat was wrong on the plate, or the thrust piece of your bolt carrier is out of spec and slamming the charging handle nipple and bushing beyond their normal range of travel, which pushes up on the receiver plate. Herbert is the smartest AUG man here in the states; he'll get you sorted out.

Spoke with Herbert today, rifle is fixed and on the way back. Pretty good turnaround time.

Charging handle assembly replaced, plate replaced and bushing repaired.

As to the bolt not locking back: Herbert said he "adjusted" the hammer spring. Apparently Steyr started using a heavier hammer spring on the semiautomatic AUGs a few years ago and it can cause issues, Herbert didn't agree with this design change. I'm not sure how a hammer spring can be adjusted, maybe he just installed another one from a full auto hammer pack. Regardless, I'll take his word it's GTG. He certainly seems to know his stuff.

Looking forward to getting it back!

Awesome!

And yea, AUG hammer springs are ridiculous

First range trip today since I got it back. First mag was a 42 rounder, bolt locked back. Second was a Steyr 30 rounder, bolt locked back. Third, was the PMAG and bolt didn't lock back Ammo was CBC M193, pretty hot stuff.

Later on at home, I pulled the hammer packs out of both my AUGs to compare. I notice that the bolt catch spring on the problem gun has more coils visible than my other. When peeking through the little cutout on the front of the pack I can see 4 coils, on the other I see 3 coils. This leads me to believe the one has a longer/stronger spring than the other. I could see how too strong a spring could cause the bolt not to lock open because the magazine follower doesn't have enough force to fully engage the bolt catch before the bolt rides over it. It even feels just a slighter bit heavy when manipulating with my finger.

Really getting frustrated with this, I might even tear down the hammer packs and compare bolt catch springs on both to test my theory. How difficult is it to remove/install the hammer? They seem to be under a lot of spring pressure.

Just keep shooting it. I doubt Steyr would have tested it with 3rd party mags

It happens with Steyr mags too, it just happened to be a PMAG this last time.

Well the bolt catch springs are identical, stupid theory in hindsight

Swapped out hammer packs with my other AUG.

Loaded all my mags (x32 of them) with at least 10 rounds, some with 20 rounds. So x10 30 round Steyr mags, x12 Steyr 42 round mags and x10 Pmags. So about 400 rounds, ammo was IMI M855. Gas setting on normal.

Fired all mags and bolt locked back everytime, no issues. This rifle has never gone more than x5 mags without the bolt failing to lock back, so this was a nice range trip. Looks like something is out of spec here, probably just going to buy a new hammer pack and hopefully put this issue to rest. Tired of screwing around with this thing, $2k rifles should work right out of the box

Let Steyr know. Maybe they'll swap the hammer pack

Ok, I’ll ask a dumb question... as I haven’t really played with the new AUG’s in quite a while and had an original AUG in the 80’s for like a minute... don’t ask, never should have gotten rid of it!! Does your rifle have a “unguarded” bolt hold open/release lever on the left side of the receiver?  I remember MSAR had made theirs somewhat guarded. If so, are you possibly bumping it with your face inadvertently while shooting it. Similar to the problem I have when shooting my pistols “thumbs forward”, which is why I’ve stopped doing it. Or possibly the lever is binding or has too much play in it? Just some thoughts.

Can't speak for OP but I would find it hard to inadvertently hit the bolt release just plinking with the rifle at the range. And one would know if their face was hitting that metal button on accident.

If OP is wearing a loaded up plate carrier or a thick jacket perhaps it's more probable to be the cause though.

The lever is in a spot where it is shielded by the hump that runs lengthwise on the AUG. I had to hold my AUG at a very odd angle to get it to contact my face. I even did a few mag dumps yesterday shooting from the hip and the rifle tucked into my side right by the mag catch, no problems. The bolt release lever is pretty sloppy on both my AUGs, no noticeable binding, they swing around pretty easy.