GB Hammer and Spring Installation: An Easier Way

Installing the hammer and hammer springs on the Steyr GB can be challenging because each hammer spring must be wound and its fixed (hooked) end inserted into a cavity in the underside of the sear (Figure 1). This can be done using some thin steel wire, a hook tool or dental pick, and a flat screwdriver for turning the grip screws. The method is shown for a GB with the later spur hammer. It should work for the ring hammer version as well but I haven't tried it. This was inspired by a previous post from Patm in Feb 2010 who used wire to hold the hammer springs in a different way. Thanks!


Figure 1. Hooked end of a hammer spring fits into this cavity in the sear.

Safety note: Since you are working with springs under tension, always wear safety glasses.

Step 1. With grip panels removed, secure lower front of the frame in a soft-jaw vise. Tighten only enough to hold the frame securely and use care not to bend the frame. Leave the lower grip screw holes exposed. Install a grip screw about two turns into each lower hole.

Step 2. Place hammer springs on the hammer studs in the orientation shown (Figure 2). The straight end of each spring fits behind the "tee" projection on the hammer.


Figure 2. Hammer springs fit onto the hammer like this.

Step 3. Install hammer pointing downward into magazine well with hooked end of each hammer spring pointing upward (Figure 3). If necessary, pull the trigger slightly to make room for the hammer to pivot into position. Install hammer retaining pin.


Figure 3. Install the hammer pointing downward and the hooked end of each hammer spring pointing upward.

Step 4. Cut two 18" lengths of thin steel wire and bend each length in half to form a loop. Insert the loop end of one wire into the frame's left magazine well cutout, route the wire in front of the hammer assembly, and place the loop over the hooked end of the left hammer spring. Wrap wire one turn clockwise around the left lower grip screw and tighten grip screw just enough to secure the wire. Repeat the process for the right hammer spring (Figures 4 and 5).


Figure 4. Fit wire loops over the hooked end of each hammer spring.


Figure 5. Wrap the free ends of the wire clockwise under the lower grip screw.

Step 5. Rotate the hammer toward its upright "at rest" position. Adjust wire length through trial and error until the hooked end of each hammer spring is pointing slightly forward of the vertical when the hammer is fully upright (Figures 6, 7, and 8). The trigger arm will hold the hammer in this position. If additional wire length adjustment is necessary, the hammer can be released again by restraining it, pulling the trigger, and easing it forward. If the hooked end of the right-hand hammer spring becomes caught under the frame rail (Figure 8) pull it free with your hook tool.


Figure 6. Hammer in its vertical position with wires holding the wound-up hammer springs.


Figure 7. Left hammer spring in its proper orientation.


Figure 8. Right hammer spring in its proper orientation.

Step 6. Install the sear and sear pin (Figure 9). The hammer may need to be pulled back slightly during sear installation.


Figure 9. Sear is installed and secured with its pin.

Step 7. Remove wires from the grip screws and cut each wire to leave a short stub.

Step 8. Use your hook tool to pull the wire stubs out from rear of frame (Figure 10).


Figure 10. Removing wire stubs with hook tool.

Step 10. Reinstall grip panels, cock hammer, and reassemble your GB.

 

This is very interesting. Can you insert the parts into the frame and install the pins? If so, this is far superior to a method that requires wire and tools.