Steyr AUGA3 design details with pics.

[briansmithwins]

Review of Steyr AUG A3 design details and wear at 1000 rounds. I included some AR parts for comparison since many people are more familiar with those.

Steyr AUG A3 with Surefire X300 on the side rail, Aimpoint Micro on a KAC mount and HK416 sights as BUIS.


Basic field strip into groups. Barrel group, stock group, receiver, recoiling parts, hammer group, buttplate, light, mag, and sling pin.


Barrel group detail stripped. Barrel, gas regulator, gas piston, gas piston return spring.


Detail of barrel locking lugs.


Detail of chamber area.


Detail of gas regulator.




Detail of front of receiver. The barrel front trunnion, gas piston bushing (left), charging handle bushing (right), and barrel lock (lower right) all have steel inserts for wear.


Detail of rear of receiver. The guide rods run in steel inserts pressed into the receiver. The rear trunnion is a steel insert pressed into the receiver rear.


Detail showing rear trunnion barrel locking lugs.


Recoiling parts group detail stripped. Firing pin, bolt sleeve, cocking piece, extractor pin, extractor, bolt, and bolt carrier.


Firing pin (lower) with AR firing pin for comparison.


Bolt with captive cam pin.


Detail stripped bolt showing roll pin that captures the cam pin.


With AR bolt and parts for comparison.


Cont. in part II.

 

[briansmithwins]

Part II.

AUG extractor (hard chromed) with AR extractor. AUG extractor is wider and longer.




Width of AUG extractor.


Width of AR extractor.


AR bolt with AUG bolt for comparison.


AUG bolt lug dimensions.




AR bolt lug dimensions.




AUG bolt thickness at the cam pin hole.


AR bolt thickness at cam pin hole.


Detail of bolt sleeve.


Recoiling parts showing how bolt sleeve prevents bolt from rotating when stripping lugs of bolt contact rounds during feeding.




Recoiling parts approaching receiver.


Cont. in part III.

 

[briansmithwins]

Part III.

Bolt sleeve makes contact with rear of receiver (steel trunnion insert). Bolt sleeve is still preventing rotation of bolt at this point.


Bolt sleeve has stopped, freeing cam pin to begin rotation and start looking bolt.


Bolt partially locked.


Rear of bolt carrier. The roller at the top is visible, as is the cutaway at the top of the hole for the bolt sleeve.


BSW

 

[Sam1911]

Thanks Brian! Really wonderful details. Steyr came up with a neat way to skin the cat, so to speak.

 

[strambo]

Nice photos, the AR/Aug bolts are very similar, but I can see how the AUG bolt looks like the better design and should go a lot longer before shearing a lug. The lugs are wider, longer and rounded.

 

[briansmithwins]

Nice photos, the AR/Aug bolts are very similar, but I can see how the AUG bolt looks like the better design and should go a lot longer before shearing a lug. The lugs are wider, longer and rounded.

The AUG lugs have more area in shear and probably a better transition with less of a stress raiser at the lug base. Plus Steyr managed to fit a bigger extractor in there too!

I've actually been unable to find anyone that's had a AUG bolt lose a lug. My guess is that the stress on the lugs is less than the steel's limits, making it a part that doesn't fail, unlike the AR where crack growth from the base of the two lugs nearest the extractor happens because those lugs are overloaded. I don't know what steel the AUG bolt is made from either but I suspect it's a tougher steel than the AR bolt uses.

BSW

 

[HOOfan_1]

AUGA3 and FS2000 are the only bulloups which intrest me...but I want them