Steyr GB hammer / sear spring installation tool

Discussion in 'Maintenance / Tweaks / Technical Difficulties / So' started by Bullitt, May 13, 2020.

  1. Bullitt

    Bullitt New Member

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    Like several others I took my GB pistol apart without knowing just how tricky it would be to get the hammer and sear spring back in correctly. There's a pretty creative solution already posted here using copper wire, but I figured I could make something simpler. I designed a 3D-printed tool that makes reinstallation of the sear very quick and easy.

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    I uploaded the files to GrabCAD here. My samples were made on an SLA printer. If you have an FDM or SLS printer it should work too, but I haven't tried those personally. If you don't have access to a 3D printer, there are a number of companies that offer 3D printing services. My personal recommendation would be a company called Xometry. At the time of posting their quote tool gave me a price of about $10 for an SLS part (plus shipping).

    Anyways, here's how it works.

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    The starting point for these instructions assumes you have assembled all the parts except for the sear and sear pin. Ideally the grip panels have not yet been installed. I have the gun in a vise so I can take pictures, but it isn't necessary.

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    Pull the trigger and press down on the trigger bar. This will disconnect the hammer from the trigger bar and allow you to flip it forward into the magwell.

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    With the hammer pointing down the magwell, make sure the rounded spring legs of the torsion springs are pointing up. The right spring leg can sometimes get caught on the frame, so this is why you want the grip panels removed.

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    Insert the spring tool into the frame. The forked ends should hold the spring legs, and the step in the tool will hook into the rear ledge of the frame. Make sure the spring legs are centered in the grooves of the forked ends.

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    Pull the hammer up out of the magwell and rotate it back until it reengages with the trigger bar. The tool will hold the spring legs in place and tension the springs.

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    Reinstall the sear and sear pin. You'll have to use the sear to push the hammer back slightly until the holes for the pin line up. Careful not to bump the tool out of place.

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    Remove the tool from the frame. Pushing forward before you lift it out will save wear and tear on the step that hooks it into the frame. Your hammer and sear should now have the correct spring pressure.

    Let me know if you have any questions or feedback.
     
    silentheart, BRING_GUNS, Case and 2 others like this.
  2. Bullitt

    Bullitt New Member

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    One thing to note is that I don't know if this will work with the spur hammer variant.
     
    Case likes this.

  3. BRING_GUNS

    BRING_GUNS New Member

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    That's awesome, and good timing for me as I recently bought a SLA printer AND found out my hammer spring was broken so I'll be messing with it a lot trying to find a suitable replacement.

    Speaking of which if you have a set of calipers handy would you mind telling me what the wire diameter of your hammer springs is? Outer diameter and width of the spring would also be extremely helpful if you have the time. The springs on my fairly early production (September 1982) GB have a wire diameter of 0.045" but I've read that later guns had slightly different springs with a thinner wire diameter and an extra coil (5 1/2 coils vs 4.75 or so on the earlier springs).
     
    Bullitt likes this.
  4. Bullitt

    Bullitt New Member

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    I measure the wire to be 0.037" and the OD is 0.391". The spring has 5.5 coils and a width of about 0.265". Note that there is relatively significant spacing between the coils and it can be compressed down to about 0.226".
     
    BRING_GUNS likes this.
  5. BRING_GUNS

    BRING_GUNS New Member

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    Thank you so much!
     
    Bullitt likes this.
  6. Bullitt

    Bullitt New Member

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    No problem. It's good timing that I have my calipers at home because I've been working remotely.
     
    BRING_GUNS likes this.