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Awhile ago I built a 1911 .45 ACP from parts using an 80% frame.  I milled the slide rail slots in the frame, and hand-fitted all parts to produce a fully- functioning, reliable 1911 pistol.  I have used this gun successfully in a number of 3-gun matches, and it is now my concealed carry gun.  Yes, I would trust my life with this gun.

Unfortunately I’ve never been very pleased with how the trigger fit in the frame.  It seemed like the trigger slot in the frame was cut too large which allowed the trigger to wobble, both vertically and horizontally.  The vertical movement would definitely affect trigger let off; if I moved the trigger shoe up the pull was nice and crisp.  If I moved the trigger shoe down, the let off had some creep.  There’s almost nothing worse than an inconsistent trigger to affect accuracy.  I was discussing this with a gunsmith friend of mine who specializes in 1911’s and he suggested that I make my own trigger.

Removing the Stirrup
I took a spare trigger I had laying around the shop and removed the stirrup from the trigger shoe.  The steel stirrup is staked in the aluminum shoe by two stamped indentations as you can see in Figure 1.  I took my Dremel tool with a cut-off wheel and carefully removed aluminum from around the stirrup on the side away from the over travel screw until I could remove it from the trigger shoe.

Fabricating a New Trigger Shoe
I purchased a 3/8” x 1 1/2” x 12” piece of aluminum bar stock from Online Metals.  The 1 1/2“ width allowed me to cut two trigger shoes side by side.  I measured the trigger shoe slot in the frame and using my CAD program I designed a new trigger shoe that was .937” high x .66” wide x .268” thick.  I made the height and thickness a couple of thousandths larger than they needed to be so I could finish final fitting by hand.  I laid out two shoes side by side as shown in Figure 3 so I could cut them both out at the same time.  I set up my hobby CNC mill and using a 3/16“ flat end mill I first milled the surface of a 1 1/2“ square section down to .268”.  Then, using the same bit, I cut out the two trigger shoes.  Note that even though I used a CNC mill to cut out the shoes, the same can be accomplished with a hacksaw and files, but it will take a lot longer.

Fitting the Trigger Shoe to the Frame
First I beveled the top and bottom edges to 45 degrees.  This allowed the shoe to fit in the cut in the frame even if the corners of the slot are not exactly square.  Then I laid a sheet of 320 grit wet/dry paper on a flat surface and began polishing the sides of the shoe until it would fit in the slot.  To test the fit I inserted the shoe lengthwise in the slot to see if it would fit in both the top and bottom as shown in Figure 4.  I continued to polish until it would fit.  The final thickness was .266”.

Next I again used the 320 grit paper and polished the top and bottom of the trigger shoe until it would move freely in the cut-out in the frame.  The final height was .935”.
  
  
  
  
  

Radiusing the Front of the Trigger Shoe
At this point the trigger shoe fit in the frame perfectly; it moved freely with no top to bottom or side to side wobble.  But the front was flat with a sharp edge, which I need to remove.  I put a fine sanding drum in my Dremel tool and removed the sharp front edges of the shoe on each side.  This put a gentle radius on the front of the trigger.  I finished polishing this surface with some 320 grit wet/dry paper wrapped around a 3/8” wooden dowel chucked in my drill.  I ran the drill at a medium speed and polished the front of the trigger shoe until no more scratches from the sanding drum could be seen.

Drilling the Over Travel Set Screw Hole and Cutting the Stirrup Slot
Next I drilled the hole for the over travel set screw, and cut the slot for the stirrup to set in.  First I wrapped the trigger shoe with some masking tape to protect the surface, then squared and leveled it in a machinist’s vise on my CNC mill.  I used a #36 drill bit and drilled a hole .208” up from the bottom of the trigger shoe.  This will eventually be tapped for a 6-32 set screw.

The slot for the stirrup should be .054” wide, and in the center of the shoe.  Ok, now to oil the rusty brain cells.  The shoe is .266” wide; subtract the width of the slot .054” leaves .212”.  Divide that by 2 gives you .106” on either side of the slot.  I’m using a .04” wide end mill bit, so if I start at the edge of the shoe, move the bit .106”, that will put the center of the bit over the near edge of the slot.  I have to move the bit an additional .02” (half the diameter of the bit) so the edge of the bit is cutting at .106”.  I cut this slot until the depth reached .132”.  I move the bit another .014” and cut to a depth of .132” so the final width of the slot was .054” (bit width of .04” + .014” = .054”).  I removed the shoe from the vice, removed the tape, cleaned up the edges, and tapped the over travel hole with a 6-32 tap.

Setting the Stirrup in the Shoe
When commercial manufacturers assemble the stirrup to the shoe they use a jig.  I used the pistol frame as a jig.  First I used acetone to clean the slot in the trigger shoe and that part of the stirrup that fits into the slot.  I put a drop of epoxy in the slot and carefully inserted it into the frame from the front (through the trigger guard).  Then I inserted the stirrup through the rear of the frame until it was inserted into the slot.  I was very careful not to spill any epoxy or I might not be able to remove the trigger.  I was also careful to make sure the stirrup was installed correctly.

After the epoxy set up I removed the trigger from the rear of the frame and set the shoe in my vise.  I used a prick punch to make indentations in the aluminum on either side of the stirrup bar to stake the stirrup in place.  The stirrup was now solidly in place and did not move.

Finally I removed the trigger, put a drop of Loctite blue in the over travel screw threads and inserted a 6-32 x 1/2“ set screw.  I reassembled the frame and adjusted the set screw until the hammer would fall without having the half-cock notch touch the sear.

I once again disassembled the gun, lubricated the new trigger, and reassembled the entire gun.  Now, my new trigger has very minimal wobble, and the trigger pull is consistent.  Finally I’m pleased with my project.