Milling A Glock Slide (August 12th 2015)

Here's a quick project I did for a friend's Glock 20 in 10mm. He wanted to put a Trijicon RMR 3.25 MOA adjustable red dot sight on it which called for a section of the slide to be milled out and to drill and tap two 6-32 holes. The only problem is I don't own a milling machine, so I had to run what I brung and use my lathe.

The miniature reflex sight and an optional baseplate.

Since I don't have a milling machine, I had to use my lathe in an unconventional way. I first took off the three jaw chuck and put on the faceplate. Then I lashed an angle grinder to the faceplate with some parachute cord and a Spanish Windlass. Then I spent a good while with indicators getting the compound parallel with the lathe's ways, and the grinding wheel perpendicular. Then I used three C clamps to clamp the pistol's slide to the compound. Again, I used an indicator to get the slide level. Some paper towel serves to prevent scratching the slide, although that Tenifer (ferritic nitrocarburized) coating Glock uses is hard as a rock. I originally thought I'd just file the slot by hand, but a file can't touch it.

Here's an action shot. I put a cutoff wheel in the angle grinder since I figured the cutting forces would be less than a wider grinding wheel which would help my sketchy setup in the rigidity department. The axis of the angle grinder is slightly offset from the axis of the faceplate, so I can rotate the faceplate a fair amount and only change the depth of cut slightly. The slot ended up being about 1.800" long and .075" deep. I covered the ways of the lathe and as much as I could of the carriage to keep the abrasive grinding dust out.

I ground out about .010" per pass and just moved the carriage back and forth slowly. Once I got close to depth I moved the cross slide from about .100" per row to about .030". This resulted in a very nice surface. Using a 4.5" diameter wheel, then that results in a 0.00005" tall ridges between rows. Not enough to even measure with my equipment.

Next I used the baseplate to mark the location for the two holes and I drilled them with a #32 bit for 50% thread engagement. I used a drill press for this operation and I think I hit the extractor plunger or something on the far hole. It shouldn't cause a problem since I just barely touched it, but it's something to watch out for if you're milling a Glock slide.

Then I went in with a 6-32 tap and tapped the holes. I used the drill press to hold the tap vertical, but rotated the chuck by hand.

Here's the sight screwed into the slot.

Once the gun was back together, it was off to the range to test it!

Here's the target from 10 yards shooting offhand with .40 S&W rounds. The first group showed it was shooting way left, so I corrected that by a full turn of the windage dial. That put the sight pretty much dead on. Then I tried 10mm rounds at a different target to see how they did. The two holes in the "wind gust" group were from the 10mm. I find this gun really hard to hold because the grip is so big. I don't have much experience shooting it and I was anticipating the recoil a bit as well.

The finished product.

His holster needed some minor modification because the sight hit the kydex shell. I cut out a small section with a cutoff wheel in a Dremel and smoothed the edges with some needle files so the gun would seat all the way down.

Milling Another Glock Slide (April 2nd 2016)

The same friend recently bought a Glock 29 in 10mm and he wanted me to put on a
Vortex Venom 3 MOA adjustable red dot sight. This time it was much easier because I've since bought a milling machine.

Vortex Venom 3 MOA red dot sight, 1/4" carbide end mill, and the victim.

Mill out a slot down to the depth of the rear dovetail.

Drill and tap two holes for the #6-48 screws.

The sight has a slight radius, so use a judicious amount of sharpie to paint where the metal will show. Loctite the screws in.

Aimbot installed.

Just like holding a 2x4.

It's a good to have some idea of what you're doing rather than winging it.

I found this gun really hard to shoot. 10mm is so snappy and this gun is fairly small that it's hard to get fast follow up shots. It's also super easy to shoot to the left. I don't think I'm anticipating the recoil, it's just I have a hard time with the grip.