Disassembly/Reassembly of the Steyr AUG Bullpup, Part 2

For those of you who have read the first part of this article on the Steyr AUG, and even those who haven’t, I’ll start with a warning. When initially stripping down an A3 leave the safety on. Otherwise, you might inadvertently pull the trigger and release the hammer forward. Do so, and you can begin forgetting about removing the trigger group from its home in the butt stock. The hammer is under pressure from two springs, one on each side, and both are very strong.

Groping into the butt with a hook of some sort and latching on to the hammer in an attempt to recock it is unlikely to be successful. The rifle will have to be reassembled to a point where you can manually cock the bolt. This will put plenty of leverage to work for you in resetting the hammer. All this frue-frue can be avoided if the safety remains engaged to block the trigger and sear. The sear, by the way, doesn’t resemble any part of the same name and function you’ve likely seen before.

My Abest analogy is that it looks more like a fairly long, two-tine table fork made from drill rod. Before adding more information on the sear, the trigger mechanism itself merits further discussion. The trigger is a "pull through" system, similar to the Glock "Safe Action" system. The accompanying diagram shows the trigger mechanism at full cock with the sear engaging the hammer and the drop safety activated.

Should the rifle be dropped muzzle downward while cocked, this safety (16) rotates forward to block the trigger group slide (8). After it has done its job, the safety returns to its original position. Moving right along, I’m assuming you’ll have no problem removing the trigger group from the butt once the hammer was released. Press down on the cocked hammer (5) and separate the slide (8) from the assembly. There are two identical mechanism pins (9). A 4mm drift is used to push them out right to left.

The rearmost pin is the first but don’t push it all the way through the mechanism body (1). B Only go far enough to withdraw the bolt retaining lock (12). Apply the drift to the front mechanism pin and push it clear out of the body. This accesses the trigger spring (13) and disconnector lever pin (11) for removal. Return to the rearmost mechanism pin. Push it out the rest of the way to remove the drop safety and its spring. Drift out the hammer pin (15).

Remove the hammer with its right spring (6) and left spring (7) attached. After memorizing how the springs and hammer are united remove the springs. Don’t get them mixed up. The right side spring can’t be made to reinstall on the left side of the hammer. The same is true of the left hand spring and the right side of the hammer. Oh, I suppose these springs could be bruteforced into submission but if they were the entire trigger group would be useless. Let’s try to do things the way the Austrians intended.

The hold open catch (2) is located at the extreme rear of the trigger group. It has two holes in it. The lower one opens to a slot. Working from inside the body, use a 2mm diameter drift to push out the catch pin (4) from the upper hole. What’s in the lower hole, the one with the slot, is the coupling pin (17). Lift up on the hold open The sear (A) has engaged the hammer and the drop safety (B) is active.

Should the rifle be dropped muzzle downward while cocked this safety rotates forward to block the trigger group slide.

catch until the coupling pin pops out far enough to align with the slot then slide the pin down and out of the trigger group. Remove the catch and its spring (3) as a unit. Separate the two components. Make A Reassembly Tool Your primary material can be a fl at of cold-rolled steel. I prefer a fl at of Aluminum for easier machining. You could also use rounds but sooner than later you’d have to solder or spot weld a spacer between them.

The Steyr factory assemblers employ what they calla "fit up" aid for hammer installation. You’re about In this position tighten the trigger screw (2) and trigger washer (3). to build your own because they are not available outside the factory. It would be great if they were but since they aren’t I’ll simply state that reinstallation of the AUG A3 hammer without one can generate a massive migraine.

Though he couldn’t, or wasn’t allowed, to provide exact dimensions I could pass along, Steyr’s top domestic gunsmith told me the tool resembled a tuning fork. Each of the open ends on the tool has a single hole center drilled in it slightly larger than the diameter of the hammer springs and about 1/8" deeper than their straight leg. Once drilled, the "fork" has to fit up into the body through the two rectangular openings at its bottom.

If round stock is your choice of base material, this is where the previously mentioned spacer comes in. It must be wide enough to allow easy passage into and upward through the rectangles while serving as a handle for the open end of the tool. Flat stock would require a slot to be machined out between the fork tines. The question likely to be arising at this time Start with the rearmost pin (A) don’t push it completely out. Remove the front pin (B) to access the trigger spring (C) and the disconnect lever (D).

is, "Where should I drill the holes in the two fork tines?" Here is the answer. With the springs mounted on the hammer, measure the distance, center to center, between them. Transfer this to the upper ends of the fit up tool. The next question likely is, "How is the tool used to reinstall the hammer?" The springs are on the hammer with the long leg of each spring corresponding to its hammer recess. Insert the tool into and upward through the rectangular body slots.

Capture the shorter spring legs in the tool holes you drilled for them. Maintain contact as you position the hammer with its cartridge impact end upward. Continue the contact as you slide the hammer down into the body.

Align the hammer pin holes, install the pin and withdraw the tool. 1 BODY, TRIGGER MECHANISM A3 SA 2 CATCH HOLDING OPEN A3 3 SPRING, CATCH HOLDING OPEN 4 PIN, CATCH HOLDING OPEN 5 HAMMER SA 6 SPRING SA, HAMMER RIGHT Improved Trigger Pull As you have seen in the diagrams here, the sear engages the hammer. While the sear is made of metal, as you would expect, the hammer, however, is constructed of a polymer material. There is the rub, so to speak.

You can carefully polish the sear engagement angles and its nose but that is it. Period. To remove the sear for the polish job, and maybe to add a drop or two of molybdenum disulfied-laced hydraulic fluid afterwards, use a size three hex wrench and a set of smooth jaw parallel pliers, available from Brownells, of course.

Referring back to the diagram on trigger fitting procedure on the bottom of page 4, back off the trigger screw (2) and pull the sear (6) from the butt subassembly (1) with the pliers. 7 SPRING SA, HAMMER LEFT 8 SLIDE, TRIGGER MECHANISM 9 PIN, TRIGGER MECHANISM 10 LEVER SA, DISCONNECT 11 PIN LEVER DISCONNECT 12 LOCK, BOLT RETAINING Sear Adjustment The clearance between the trigger (4) and the butt subassembly should be checked and adjusted if necessary.

Insert the trigger into the butt assembly and install the sear from the rear of the butt. Push it forward until it stops. Install the cocked trigger mechanism and secure it with its retaining pin. Slide the sear back until it rests against the trigger mechanism guide but does not release the hammer. Tighten the trigger screw and washer (3). Combining Parts I and II, you should be able to maintain all AUG A3 Bullpups that come your way. I suggest you hang on to your fit up tool.

There are sure to be a goodly group of gun owners who fancy the idea of a lightweight, quick-handling short rifle that puts out long barrel rifle performance. AG Steyr AUG Trigger Group (Speci cations subject to change without notice) 13 SPRING, TRIGGER 14 BOLT RETAINING, SUB-ASSY. 15 PIN, HAMMER 16 DROP∙SAFETY, SUB-ASSY. 17 COUPLING PIN A3