Custom 1911 Project: Part 2-undercut trigger guard

Custom 1911 Project: Part 2 undercut trigger guard- Presented by and Brownells

This is the second installment of our Custom 1911 project- in this post we are going to undercut the trigger guard area of the frame.

  1. Custom 1911 Project: Part 1- getting started
  2. Custom 1911 Project: Part 2-undercut trigger guard
  3. Custom 1911 Project: Part 3- fit and blend grip safety
  4. Custom 1911 Project: Part 4- Machining a chain link front strap
  5. Custom 1911 Project: Part 5- milling the slide for low mount sights
  6. Custom 1911 Project: Part 6- flat top and chain link top of slide
  7. Custom 1911 Project: Part 7- machining ball cuts on a 1911 slide

custom 1911 full right side of pistol

Our custom Remington R1 is outfitted with the following Wilson Combat parts:

Undercutting the trigger guard on a 1911 pistol allows the shooter to gain a high grip on the pistol.  This modification, along with an aftermarket grip safety can significantly improve the handling characteristics of the pistols for some shooters by moving the shooting hands closer to the axis of the bore.

For reference purposes during this post, please refer to this schematic of a Colt government model pistol.

R1 before right side R1 casting marks on frame

If you take a close look at the front strap of our Remington R1 project gun, you can see how the frame comes from the factory.  Note the casting marks that are visible down the center of the frame.  While I don’t have a problem with cast frames (some guys only like forged frames), one very real downside is they could potentially contain voids.  This means that when you start cutting the frame, it is possible to expose a void which could potentially be a visual or structural flaw.

Besides a void, what else could go wrong?  You could potentially cut too far into the frame and ruin it.  That means that prior to any cutting the work areas should be carefully measured.

Before we proceed, please read the following disclaimer:

WARNING: The contents of are produced for informational purposes only and should be performed by competent gunsmiths only. and its authors, do not assume any responsibility, directly or indirectly for the safety of the readers attempting to follow any instructions or perform any of the tasks shown, or the use or misuse of any information contained herein, on this website.

Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.

Modifications to a firearm may result in personal injury or death, cause the firearm to not function properly, or malfunction, and cause the firearm to become unsafe.

A trigger guard can be undercut with either a machine or hand tools.  Since I have access to a milling machine, I used it.  I’ve seen some great work with a set of files, so don’t feel bad if you don’t have a milling machine and want to try this on your own with hand tools.

R1 1911 undercut trigger guard set up

To set the frame up on the mill, I removed all of the parts from it.  The frame was then seated on a pair of 1-2-3 blocks and clamped to the table.  The clamps are carefully placed so as not to bend the frame.  Card stock is used to prevent the clamps from marring the surfaces of the frame.

Originally I envisioned calculating a precise angle and setting the frame up based off of that.  However, when I got into the math and set up I decided that I could do as well with my eyes- it is a custom build after all.  To align the frame on the mill I simply eyeballed the intersection between the front strap and and top of the frame.

r1 1911 undercut trigger guard with end mill

I chucked a 4 flute 3/4″ end mill in the milling machine and centered it up where the frame and trigger guard met and zeroed the digital readout (DRO) on the milling machine.

r1 1911 undercut trigger guard with end mill 2

No point in trying to be a hero here.  I simply moved the X axis .005-.010″ at a time to the right and made a slow plunge cut with the end mill.  Once the cut was complete, I retracted the end mill, moved the piece to the right and made another plunge cut.  I cut this frame approximately .090″ in.

R1 1911 undercut triggerguard coming off milling machine

The final cut feels great, I am very happy with it.

r1 sideview of undercut triggerguard

Here is a side view of the same cut.  Note how much higher I can now place my hand when firing (compared to the frame as provided from the factory in the photos at the beginning of the post).  A little bit of polishing with some abrasive cloth and it is ready to be finished.

custom 1911 front strap chain link

A view of the high undercut trigger guard on the finished pistol coated in Cerakote.

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