Building A Custom Glock Pistol (Part 2)

Shueyby Gene Shuey
AGI Instructor and Master Pistolsmith

Master Pistolsmith Gene Shuey finishes his article on building a custom Glock suitable for duty, range, or self-defense. If you missed Part 1, click here.

Sight Considerations

There are more options for sights than probably anything else. Sight manufacturers continue to come out with different sights all the time. Some new Glock owners have trouble with the sights because they’re basically a point of aim sight or, in other words, a combat sight.

Night Sights

I usually ask owners what kind of sights they have on their other guns. Sometimes they’ll have night sights but will never shoot at night. They may want you to add night sights because the magazines or their buddies tell them night sights are good. But, night sights may not be the best suited for the gun’s use.

There are several different types of night sights. Some are better than others. For example, some night sights have three little donut-like circles surrounding the tritium element. The donuts can be distracting if you are shooting in daylight.

For night sights, I prefer the Heinie Straight Eight. They look like a figure eight, one ball over another. In the daylight, you can’t see them but at night, they shine brightly, thus there is no distraction in the daylight. You’re covered both ways, daytime shooting and in real-world low-light situations.

Fiber-Optic Sights

There are different size fiber optic elements and different colors. Sometimes when shooters get older or have diminished eyesight they’ll use two colors, like red in front, green in back. Having a different color for the front sight makes it easier to put it in the center, equally spaced between the rear sights and even on top for the height.

Stock small and large frame Glocks and their two different styles of backstrap checkering.

Stock small and large frame Glocks and their two different styles of backstrap checkering.

The one sight that I don’t recommend is called the XO or XS sight. That’s the one that was commonly used on express rifles. It has a very shallow V for the rear sight, and the front sight is a great big white golf ball.

The problem with these types is it’s hard to do precision or accurate shooting. It’s basically point of aim type of sight. Most of your targets will be covered with the big white ball for the front sight. If the subject is that close to use that type of sight, you don’t need a sight at all. That’s why I don’t recommend them.

So you basically have three different types of sights to choose from, black sights, fiber optic and night sights. Within each one of those categories, there is a great selection. For example you can get a wide sight, or a narrow sight. This will determine how much light you’ll see between the front sight and the rear sight.

This is why it’s so important to ask questions before recommending any type of sight. How good are their eyes? What kind of sights do they have on their existing guns? Of course they could also have their own preference.

If it’s a carry gun, it’s also important to know how they plan to carry it. That is going to dictate the shape of your front sight. If it’s a target sight with sharp edges, when he puts that in his waistband and pulls it out, he’ll probably pull his skivvies out with it or cut his skin. Or  if it’s a leather holster, shave off a little bit of the leather from the inside that could end up on the front sight.

This is why it’s so important to ask questions and have a variety of sights you can show, preferably already mounted on guns or at least on extra slides.

Barrel Considerations

We’ve already discussed barrels but the heart of a gun is the barrel so let’s consider a few more factors. If the barrel is not an accurate barrel, there is nothing that you can do to the rest of the gun to make it accurate –nothing. So, if you build a very expensive gun and/or very reliable gun, or an attractive gun, or the gun of your dreams,  put a good barrel in. Because, if it doesn’t shoot straight, it doesn’t shoot with accuracy.

Think about it like an equilateral triangle. All three legs are equal and the same length. One leg of that equilateral triangle is reliability. The second one is accuracy. The third one is quality of work and distinction of appearance. Each one is equal. When you think like that, you will be head and shoulders above 99% of the gunsmiths in the world –not the country –in the world. Keep that in mind. So, if you’re going to build a good gun, put a good barrel in.

If you use an inexpensive $90 barrel, it may be somewhat accurate, but how well is it made? What kind of material does it use? How good is the heat-treating? What is the geometry? When I say geometry I’m referring to the locking lugs, the hood on the barrel, and the concentricity of the bore to the chamber. That’s very important. I know of several offshore barrels and some American barrels that are very cheap. Some of these have had failures. They could split, crack or separate. That’s usually because of bad alloy, bad material, or bad heat treat. Good barrels have good rifling; their chamber is concentric, and it’s within SAAMI Spec. Usually the rest of the geometry will be right on the money. For a gunsmith fit barrel, you will have to make some measurements and fit the hood, the length of the hood and possibly the width of the hood. The locking area, where it rides up on the locking block, may have to have five to fifteen thousandths trimmed off. You can use a mill or file to do this.

Although any of this can be done by watching AGI’s step-by-step videos, for your first few times I suggest using a good drop-in barrel. There are several. Bar-Sto makes one; KKM Precision makes a very good and extremely accurate barrel for a drop-in. I have one of the few barrel testing machines in the country, and when I build a high-end gun, I will select the barrel from the manufacturer and test it.


Here’s a little history about what I’ve learned from testing. I started building 1911s about 50 years ago. I would build them, shoot them from a bench rest to print a group and give the target to the customer. But fairly often the customer would later return and tell me the gun wasn’t accurate. I would test it again and it would be dead on. The problem was with sub par ammo.

I learned a long time ago –when the customer comes in, I ask: What kind of ammo do you use? Do you reload? I would have the customer bring in or send me his ammo and magazine. With a Glock it’s not important to have the magazine, but other guns it may be. I found at least 70% of the time the customer’s ammo was sub par. All your customer knows is that he pulls the trigger and it’s not in the bull’s-eye. If you don’t educate him about the ammo, they’ll assume you didn’t do a very good job customizing the gun.

Trigger Options and Aftermarket Parts

There’s also a wide variety of options when it comes to triggers. This creates a problem because the amateur or the guy off the street will pick up a catalog and purchase a brand X connector, brand Y springs and try to use it with his brand Z trigger bar. He puts it all together and guess what? It doesn’t work.

It doesn’t work because of the different geometry. Glock is not a precision gun. But it will always go bang by using the Glock design and parts. We Americans want precision and accuracy and speed so we start playing with the geometry, by replacing Glock parts with aftermarket parts. It’s a crap shoot whether it will work or not.

Here’s what I do to solve this. I buy parts and I have companies send me parts, and I test them. I will mix and match and find the idiosyncrasies of the mixed and matched parts. But the average gunsmith won’t do this. It can really get confusing because you also have different generation Glocks. Some of the aftermarket parts work better in some generations than others. Even if there’s nothing wrong with the parts, they just don’t all work well together.

Here’s how this could affect a carry gun. To improve the trigger we might start replacing a lot of the stock parts with aftermarket parts. As I mentioned earlier that can easily cause you problems because of the geometry.

Instead of replacing all the trigger parts, I modify or enhance the existing parts. That keeps us from having the problems of using mix-and-match parts. In this case, instead of replacing everything, the only two areas that we╒re going to change are the three springs and the connector. We╒re going to keep everything else the same but you, as the gunsmith or the gun owner, are going to polish the part. It’s really simple; it’s going to give you a 90% improved trigger that’s going to work better than the aftermarkets but cost less than $25. Isn’t that better than going out and paying $300 for sophisticated trigger bars?

Not only is it going to give you a better trigger but it’s going to be reliable. That’s the key to a carry gun. We want reliability. Changing out the springs and the connector, polishing it the right way, is going to give you a great trigger and a reliable trigger. For a carry gun, you want it to go bang every time when you want it to go bang.

I show you how to do this in the AGI video courses as well as a grip enhancement step by step. All you need are very simple tools, a Dremel tool and a couple of sanding drums and a file.

Thumb Safety

Glock safetyThere are some real advantages to the Cominolli thumb safety. When you have it on, you can’t pull the trigger. But you can still load it and unload it and work the slide, which means you’re not going to have an accidental discharge.

Here’s another advantage of the thumb safety. Everyone who knows anything about the guns knows all you have to do is pull the trigger on a Glock and it’ll go bang. But with the thumb safety on, say you’re walking down the mall and you drop it or some thug walks up and pulls it out of your holster. When they try to pull the trigger, it doesn’t work. That’ll give you a chance to take remedial action.

Some Glock purists cringe at the idea of putting an external thumb safety on a Glock. But we are simply making it safer with an auxiliary safety. In addition, we aren’t voiding the Glock warranty.


Along with the things we’ve already discussed, other fairly easy things to do are extended mag releases and extended slide releases.

Glocks are good money makers for the beginning gunsmith. They aren’t difficult to work on and the sky is the limit with regard to what you can do to them.

© 2017 American Gunsmithing Institute. Reproduction of this article by any means without permission is not permitted.

One Response to Building A Custom Glock Pistol (Part 2)

  1. I love my Cominolli safety. I should have put one on years ago. I had too many close calls with my Glock almost accidentally going off. I also do not break out in a cold sweat every time I have to handle the gun or load it or unload it because I can put the manual safety on. Holstering the gun is much safer as well as if the trigger catches on the lip of the holster its not going to accidentally go off. Before I had this safety I seriously considered getting rid of my Glock because I did not feel it was a safe gun to handle or carry, now with the safety installed I no longer feel apprehensive with this pistol. I highly recommend every Glock user get one put on.

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