Custom Glock slide milling

The Glock has become a staple of the American shooting culture.  Thirty years ago it would be hard to believe this boxy plastic and steel gun chambered in a puny cartridge would become as popular as it has.   Along with it’s rise in popularity came increased customization of the guns.  Glock frames are melted, sanded and blended, and the slides are often machined with different patterns and sights.

In this post, let’s try to customize some Glock slides with a manual milling machine. Before we get working let’s take a few minutes to read the disclaimer below:

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.

It should go without saying that this can’t be good for your factory warranty and that removing material from a slide should be done with extreme caution.  Overzealous machining can lead to catastrophic cracks, breaks and failures.

Prior to machining it is important to pay close attention to how Glock sent the slide from the factory.  Look at the proximity of the frame grooves in the slide to the edges.  There is very little material here, only about .045″.  Machining too close to this would render the slide unusable.

Note the proximity of the extractor plunger hole to the edge of the slide (this factory Glock 19 slide was already customized).

Care should be taken in these critical areas.

Glock Slides are hard.  I’m not a machinist, but out of the stuff I’ve machined, the only thing gun related that I have ever encountered that was harder was an Uzi magazine (best made part of that gun).  So sharp, solid carbide cutting tools are a must.

With a rough idea of what I wanted to accomplish and a couple of old Glock 19 slides in hand, I decided to see what I could accomplish on the mill (I don’t have a CNC machine but I do have a digital readout (DRO).)

The set up for all of the slides on the milling machine was the same.  The slide was set in the vise on a set of parallels.  An edge finder was used to locate the front edge of the slide as well as the top and bottom.  This allowed me to determine the centerline of the slide.

Carry cuts on a Glock slide

The first operation I decided to try on the Glock 19 slide was a set of “carry cuts” sometimes called “Hi Power” cuts because of their similarity to Browning’s Model 1935.

To make the carry cuts I set the slide on a set of parallels and chucked up a 1/2″ four flute solid carbide end mill.  Cognizant of thin material where the rail cuts are in the slide, I left the bottom .200″ of the slide alone and moved the end mill .030″ deep.  I made a slow cut with the end mill.

To cut the opposite side of the slide, I simply plunged the end mill in the other side of the slide and made the exact same cut in the opposite direction.

Chamfering the top of a Glock slide

Often you’ll see the smooth radius on the top of a Glock slide chamfered for a custom look.  I decided this would look pretty good on my test slide.

With the same set up for the carry cuts, I used a 3/8″ 4 flute solid carbide end mill with a 90 degree point.  

I slowly worked my way around the slide.

This is how the carry cuts and chamfer looked straight off the mill before I got a chance to deburr or blast the surfaces.  Simple, but different.

Cutting ports and recesses in a Glock slide

Time to get a little more involved.  On my second Glock 19 slide, I wanted to add a recessed window and machine a port through the side of the slide.  For this operation I am using a 3/16″ four flute solid carbide end mill.

To cut the window I ran the 3/16″ end mill through the slide for a window that starts .406″ from the front of the slide, ends 1.894″ from the front, and is .313″ wide.

To cut the recessed window, I ran the end mill .015″ deep. I didn’t measure out the cuts I made, I just eyeballed them based on what I thought looked good.

Coming along nice.

The left side doesn’t have an ejection port so I just made a rectangle.  The port looks a little choppier in this picture than it actually is, those are just some burrs.

A quick trip to the blast cabinet and this slide is looking pretty good!

I had a blast customizing these Glock slides.  Are these modifications functional, not really, but I think they look pretty cool.  Sometimes, that is enough!

Do you want a custom Glock slide and don’t have a milling machine, check out these ready made custom Glock slides from Brownells.