1911 Sear Jig Instructions

The Colt 1911, otherwise known as the M1911 after adoption by the U.S. military, was developed by John Browning and produced by Colt. This weapon was the standard issue sidearm of the U.S. military from 1911 until the mid 1980s. As of 2011, the 1911 model is still manufactured by several firearms producers. As with all weapons, periodic maintenance is necessary. This can include a trigger and sear job. Using a sear/hammer jig allows you to keep the hammer and sear held in a stable position while performing stone work and angular alignment.

Things You'll Need

  • 1/8-inch pin punch
  • Bench vise
  • Brownell's sear/hammer jig (supplied with Allen screws and keys)
  • Stoning kit
  • Cutting oil
  • Layout oil
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Instructions

  1. Disassembly for Sear and Hammer

    • 1

      Remove the magazine. Pull the slide to the rear. Visually inspect the weapon to ensure that no live ammunition is present.

    • 2

      Depress the recoil spring plug. This is located under the muzzle. Twist the barrel bushing clockwise until it reveals the recoil spring plug. Carefully withdraw the recoil spring plug and recoil spring.

    • 3

      Cock the hammer back fully. Pull the slide to the rear until you see the slide release lever align with the circular depression on the left side of the weapon’s frame. Push the slide release lever from left to right, removing it from the frame completely. Push the slide forward and off of the frame. Remove the recoil spring guide rod. Set the slide assembly aside.

    • 4

      Pick up the frame and hold it as you normally would when firing a round. Hold the hammer in place with your thumb. Depress the trigger and guide the hammer forward slowly.

    • 5

      Depress the grip safety. Punch out the mainspring housing pin from left to right using a 1/8-inch pin punch and hammer. Pull the mainspring housing down free from the frame, while simultaneously holding the grip safety depressed.

    • 6

      Cock the hammer back fully while keeping the grip safety depressed. Push the safety lever up and pull it out of the frame. Release the grip safety and pull it off of the frame.

    • 7

      Lift up on the hammer strut. Push the hammer pin from right to left and out of the frame. Remove the sear pin from right to left. Turn the weapon upside down and allow the sear and disconnector to drop into your palm.

    • 8

      Push the magazine release inward, as if you were releasing a magazine. Keep the magazine release depressed. Turn the screw on the right side of the magazine release 90 degrees counterclockwise. Push the magazine release to the right side of the frame and remove it. Push the trigger to the rear and pull it out from the rear of the frame.

    Hammer Work

    • 9

      File the hammer hooks to 90 degrees in relation to the hammer flats using a hammer hook squaring file. File the hammer hook height between .018 inches to .020 inches. Ensure that the top of the hammer hooks are square in relation to the hook face.

    • 10

      Secure the right, lower end of the jig in a smooth jawed bench vise. Secure the hammer in the hammer vise on the jig using the 4 mm/16 mm screw. Position the hammer vise into slot B and hand tighten the jig using the provided Allen key.

    • 11

      Rotate the stoning guide upside down and position it on the top edge of the jig. Turn the height adjustment screw clockwise to move the hammer vise up until the hammer flats are level. Ensure that the hammer flats are even with the bottom side of the stoning guide.

    • 12

      Tighten the Allen head screw to hold the hammer vise in place. Tighten the vise screw using a 3 mm Allen wrench to hold secure the hammer in the jig. Turn the stoning guide right-side-up. Secure the stoning guide legs into the provided slots in the jig body. Apply a generous amount of cutting oil to the hammer hooks. Stone the hammer hooks using 6-by-1/2-by-1/2-inch gunsmith stones. Remove the metal until your hammer is proportionate with the angles required for your 1911 model.

    Sear Work

    • 13

      Place the sear into slot A on the jig. Thread the sear nut onto the sear post and leave it slightly loose.

    • 14

      Fit the hammer pin through the hammer. Position the hammer on the jig so that the hammer hooks line up with the sear face. Tighten the nut on top of the sear.

    • 15

      Remove the hammer and hammer pin from the Jig. Take off the sear insert from slot A and
      position it in slot B. Hand tighten the insert in slot B using the Allen head screw located on the back of the sear insert.

    • 16

      Coat the sear’s engaging surface using a layout fluid. Position the sear insert so the sear engaging surface is positioned above the plane on top of the Jig. Stone across the top of the sear in one direction only until the stone is level with the top plane of the Jig. Note that you'll be removing very little metal from the sear -- between .002 to .006 inches -- in order to align it with the hammer properly.