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Basic Trigger Fitting for 1911 Pistols

How to fit your trigger to the frame opening

A couple of basic 1911 facts before we get into this. First, there are probably over two dozen manufacturers of 1911 frames and handguns in the world today. None of them operate under any sort of dimensional standardization program. Dimensions and tolerances vary all over the place. The trigger cut itself is made in multiple steps with different cutters accessing the frame from at least two different openings. This contributes to wandering dimensions. Last thing to think about is this – if a manufacturer makes a run of frames and they figure out that some area in the trigger cuts got a little wonky, do you think they scrap the frames? No, they work around it, maybe by altering their trigger to accommodate the ”wonk”. Then it’s your problem down the road.


Pretty much all 1911 replacement triggers produced today are intentionally made slightly oversized to allow fitting to any 1911 frame. The opening in the frame for the trigger shoe varies a lot in size and consumers want a trigger fit that is not sloppy like factory supplied triggers, so installing a replacement trigger involves a little bit of fitting. My trigger shoes consistently measure .920”-.921” tall.


The way to handle fitting is to use a 6-8” fine cut file to file off material top and bottom until you achieve a free fit into the frame. Once you have the trigger fitting the frame, you will need to fit the over travel stop. That is the set screw projecting from the rear of the trigger shoe. It is not intended to be turned, it is locked in place and will need to be shortened as needed to fit it.


The over-travel stop is adjusted by filing down the tip until it stops the rearward movement of the trigger at a point that allows the sear to pivot and come clear of the hammer’s full cock notch and also allows the half cock notch to move past the sear nose without bumping it.


Tools Needed


A 6” fine cut mill file

A fine cut extra-narrow pillar file, sanded to fit the width of your frame’s stirrup grooves

Dial or digital calipers

Sandpaper – 120, 240 & 400 grit


Prepping your file –


Buy a 6” long fine cut file at your local home improvement store, or tool supply. I modify my files before using by reshaping the nose of the file to a round nose with chamfered corners and by removing the teeth on one or both edges. I use a belt sander and hold the file by hand, so I can tell when it needs to cool off. This will keep you from damaging the heat treat. You want the nose to be shaped so that it will be less likely to scratch or otherwise damage the parts you are working on.


Prepping your frame –


After detail stripping your frame, it is wise to clean any burs from the frame in both the stirrup tracks and the shoe opening. You typically don’t need to remove any appreciable amount of metal, just clean up the surfaces of any roughness and burrs. You can go to the point of stoning the stirrup tracks, but you don’t have to go crazy to get a good trigger pull. Be sure to get into the corners of the shoe opening as they may not be machined to have square corners due to worn broaching tools. Use a good magnifier, a strong light and look from every angle possible. After the clean up to the frame is done, wash it and scrub out the tracks a slot to get rid of all the filing debris.

Figuring out where to file on the trigger-


Start out by inserting the trigger stirrup into the tracks backwards. If you get binding right away, your trigger stirrup may be a tad fat at the rear at the corners, and/or the tracks may be tight at the rear. If it slides all the way to the front of the tracks, you now know that the stirrup width is okay and can be left alone for now.

Next, turn the trigger around the correct way and insert it into the trigger tracks. See how far in it will go, up to the point where the bottom of the shoe hits the bottom of the shoe slot in the frame. So long as you have reasonably free movement in and out, you can go ahead and see how the shoe starts to enter the slot. If your stirrups are tight or binding in the frame, you need to address them first. You must have free stirrup movement, fore and aft before you can work on the shoe.


The ins and Outs of the Stirrup-


If when you inserted the trigger backwards the stirrup was tight in the slots, you may need to file or sand a little from the outside of the stirrup. Take a before measurement and write it down. If the trigger went in freely when inserted the right way and it’s tight when going in backwards, I would file the outside of the stirrup, with a bias on the rearmost ¼ of the length, filing lengthwise and holding the trigger in your hand. If you aren’t comfortable with this, lay a piece of 120 grit sandpaper on a flat surface and stroke the trigger stirrup lengthwise on the paper, putting finger pressure on the top at the rear corner. Work it from both sides and measure periodically. When you’ve narrowed the width by .005” or so, wash the trigger and reinsert into the frame tracks and see what you have for difficulty to insert. Take some comparative measurements between the inside of the tracks at the rear and the outside of the stirrup and see what the difference is and work toward that.


This stirrup fitting business is something that you don’t run into that often, but when you do, just remember that there is no shame in asking for help from a competent 1911 gunsmith.


Fitting the Shoe –


Once your stirrup fits well enough for you move it forward into the tracks, go in until the shoe bumps against the bottom of the shoe slot in the frame, watch through the window in the frame and you can see the bottom of the shoe in contact. Move it forward and back and notice how much the trigger is lifting as it rides up onto the bottom of the shoe slot. If it has noticeable lift, remove it and file .002”-.003” from the bottom of the shoe. Be sure to file with the length, not across it. Clean the chips out of your file every few strokes. Measure the shoe’s height before you start, write it down and then once you’ve reduced it by .003” from the bottom, put it back in and see how it engages the bottom of the slot. See how far you are away from entering the slot at the top. If you are still lifting the shoe and are not starting to enter at the top, then take another .002” from the bottom. Repeat until either the shoe stops lifting at the bottom or the top starts going in at the top. From here out it will mostly be a case of filing .001”-.002” from the top, retest, file again. As you begin making movement forward into the slot, do not force the trigger in and get it stuck. At some point you may need to put a light chamfer on the side corners of the shoe, if you see contact.


Look from the back of the frame through the trigger passage while holding the frame toward a light. You will get a good idea of where you are close and where you are tight. What you are ultimately trying to achieve is a trigger that will move in and out under it’s own weight and have little to no discernable up and down play when it’s forward.

Adjusting Overtravel –

To test for trigger operation and over travel, assemble the frame, leaving out the grip safety, thumb safety and grips. Make sure the magazine catch is in place.



Cock the hammer and while controlling it’s movement, pull the trigger and hold it to the rear to see if the hammer moves at all.


Test -1B

If it does move, control the hammer with your thumb and lower it while holding the trigger to the rear. Feel to see if the hammer full cock notch comes instantly free from the sear nose, then if the hammer’s half cock notch is rubbing or catching on the sear nose



If it does not move, remove the magazine catch and try again, again controlling the hammer. The hammer should now move forward and travel all the way down without you feeling a bump where the half cock notch hits or it catches on the sear nose. This proves that the ignition system is functioning correctly.


If the hammer won’t move, or moves, but has a jerk as it ‘s full cock notch comes free from the sear nose, or if the half cock notch hangs or rubs on the sear nose; the over travel stop is too long and must be shortened.


Conventional over travel screws originated on the bullseye ranges which had rules where if you had a firearm malfunction you would get an “alibi” and be able to reshoot the string of fire. This bullseye-style of over travel screw is threaded in from a hole in the face of the trigger and held in place by a patch of dry LocTite on the screw. The patch style threadlocker is not reliable over the long haul and the screw may creep in from vibration, preventing the trigger from being pulled far enough to the rear to fire the pistol.


That’s a makes for a bad day at a competition, but has the potential for dire consequences in an emergency situation where your pistol must fire every time it’s called on without fail.


The over travel stop in my triggers is a set screw threaded into a blind hole in the back of the trigger, first wetted with LocTite 263 and then run in to bottom and jammed against the bottom. Once the LocTite is cured, the screw will not come out. This is by design.


If determined too long by the above tests, to adjust my over travel screw, you file away material from the tip of the screw until you reach the point where you can test for trigger operation and over travel with assembled frame, leaving out the grip safety, thumb safety and grips. Be sure the magazine catch is in place.


Cock the hammer and while controlling it’s movement, pull the trigger, controlling it all the way down.

The hammer should now move forward freely and travel all the way down without you feeling a bump where the half cock notch hits or rubs the sear nose.


At this point, I recommend removing the trigger one last time and file 2 more strokes from the tip of the set screw, to give enough extra over travel so that were a few flakes of unburnt powder or such get between the magazine catch and the over travel stop, the pistol should still work.

Captive Half Cock Operation-


Test to verify that the half cock on your pistol is captive. Other than Colt Serie’s ’80 pistols, 1911s have a captive half cock notch. If you look at yours and compare it to the full cock notch, you’ll see that the half cock has a short wall at the edge of the half cock hooks. The intent is that if a hammer fell to half cock, it would stop there and be caught, so the hammer could fall no further.


To test captive half cock operation verify that the chamber is empty and the magazine is removed. With the hammer at full cock, hold the hammer and pull the trigger, as the hammer starts lowering, let the trigger go forward. Continue lowering until the hammer stops on the half cock notch. Remove thumb from hammer and then pull the trigger with enough force that it would ordinarily fire plus a little more force. The hammer should stay captive in the half cock notch.


If the hammer stayed in the half cock notch, it passed the test. If the hammer fell, it failed the test.