A lot of Glock sight work starts the same way at my bench. Someone orders a set of night sights online, the box shows up, and then they notice the rear sight is a different height than the one on their gun, or the front sight comes with a screw they have no tool for. Now and then they have already tried to tap the old rear sight out with a screwdriver. The slide survives. The finish around the dovetail does not.
Swapping Glock sights is one of the simpler upgrades you can make to the pistol, and it is one of the most useful. The factory polymer sights work, but they wear, and that white outline does nothing for you in a dark parking lot. Before you order, learn how Glock sizes its sights and how they come off.
Safety First
Unload the pistol, remove the magazine, and look and feel to make sure the chamber is empty. Take every round of ammunition out of the room you are working in. Sight work happens with the slide off the frame, so field strip the pistol the way your Glock owner’s manual shows before you start.
Glock Sights Come in Heights, Not Just Styles
This is where most ordering mistakes happen. Glock does not use one rear sight for every model. On its European site, Glock lists standard rear sight heights of 6.1, 6.5, 6.9 and 7.3 mm, and front sights in 4.1 and 4.9 mm. [1] The height that ships on your pistol depends on the model.
Glock’s US store spells this out on its own night sight sets. The 6.5 mm rear is listed as standard height on the G17, G19, G22, G23, G24, G26, G27, G33, G34, G35, G37, G38 and G39. [2] The 6.9 mm rear is the standard height on the bigger 10mm and .45 frames, including the G20, G21, G29, G30 and G36, plus the G31 and G32. [3] Put a 6.5 mm rear on a G21 and the point of impact will move.
The slimline guns are their own family. Glock’s 6.5 mm set is listed as fitting everything except the G42, G43, G43X and G48, and the 6.1 mm slim set is listed for the G42 and G43. [2] [4] If you carry a 43X or a 48, read the fitment line on whatever sight you buy, because a standard Glock rear will not go into that narrower dovetail.
Aftermarket makers publish fitment charts by model. Use them. Two minutes with a chart beats a trip back to the range with sights that hit four inches low.
How Sight Height Moves Your Point of Impact
The rule is easy to remember once you picture it. A taller front sight makes you lower the muzzle to line it up, so your hits move down. A taller rear sight does the opposite and moves them up. With Glock’s fixed sights, elevation is changed by swapping to a different height. [1] Windage comes from moving the rear sight left or right in its dovetail, in the direction you want your hits to go.
Bullet weight can shift impact too, so set the sights for the load you actually carry.
Night Sights, Steel Sights, and Fiber Optics
Glock describes its steel sights as a tougher option than the polymer ones, built to hold up to holster wear. Its self-luminescent steel sights use small tritium elements that glow green in low light without needing to be charged by a light first. [1] For a carry or home-defense pistol, a tritium set is the upgrade I recommend most often.
Tritium dims with age. The isotope has a half-life of roughly 12 years, so a set from the early 2010s is a lot dimmer than it was new. A bright daylight ring on the front helps as well. Glock’s own BOLD sights made by AmeriGlo use an orange outline around a green tritium front. [5]
Fiber optic fronts are great on a range or competition gun, but they go dark when the light does.
Optic-Ready Slides Need Taller Irons
If you run a red dot on a MOS slide, standard-height sights sit too low to see through most optic windows. Glock lists separate suppressor/RDS heights for this, with rear sights from 11.1 to 11.9 mm and front sights at 9.1 or 9.9 mm. [1] The taller irons show through the glass, so you still have sights if the dot quits. Optic heights vary, so match the sights to your optic.
Getting the Old Sights Off
On most Glocks the front sight is held by a small screw that you reach from the inside of the slide. It takes a 3/16 inch hex driver, usually sold as a Glock front sight tool. [6] Some older polymer front sights were held in a different way, so if you look inside and do not see a screw head, stop and have a gunsmith look at it.
The rear sight sits in a dovetail and is a tight fit by design. Glock uses a dedicated rear sight tool, which is a sight pusher that presses the sight across the slide. [1] A punch and hammer will move it, but steel night sights are often tight enough that a punch slips and gouges the slide or chips the sight. I use a pusher every time.
Installing the New Set
The front sight is the easy half. Clean the oil off the threads and the slide so thread locker can do its job. The NRA’s armorer column on Glock sights recommends a dab of blue, medium-strength thread locker and tightening the screw only finger tight with the tool, because it is possible to over-tighten and snap that screw. [6] Use the screw that comes with the new sight, since the old one may not fit it. [7]
For the rear, center the new sight in the dovetail by eye, then check it. I look down the top of the slide, measure from each side if needed, and confirm the sight is square and not canted. If a sight seems far too tight to push, stop. Forcing it can crack a tritium vial or mar the slide.
Then reassemble the pistol and do a function check according to your manual before you load it.
Confirm Your Zero
New sights are not finished until you shoot them. From a rest at close range, fire a group with your carry ammunition and see where it lands. If the group is centered left to right but low or high, the fix is a different front or rear height. If it is off to one side, the rear sight needs to move in the dovetail.
When to Bring It to Strikepoint
If you have the right sights and the right tools, this is a job many owners can do at home. If you do not have a sight pusher, if the old rear sight will not budge, or if your new set is shooting somewhere you did not expect, bring your Glock to Strikepoint Gunsmithing. We install iron sights and night sights, drift and adjust them for windage, mount red dots on optic-ready slides, and can help you pick the right heights for your model and optic before you order. You can see current labor rates on our pricing page, or contact us to set up a time.
Sources:
- GLOCK, GLOCK Sights (sight heights and options): https://eu.glock.com/en/Products/GLOCK-Options/glock-sights
- GLOCK Official Store, GLOCK Night Sight Set 6.5: https://store.glock.us/glock-night-sights-set-6-5-pkg
- GLOCK Official Store, GLOCK Night Sight Set 6.9: https://store.glock.us/glock-night-sights-6-9-pkg
- GLOCK Official Store, GLOCK Night Sight Set 6.1 Slim: https://store.glock.us/glock-night-sight-set-6-1-slim-pkg
- GLOCK Official Store, GLOCK BOLD Sights by AmeriGlo: https://store.glock.us/glock-bold-sights-by-ameriglo-pkg-1801
- NRA Family, Hints From Our Armorer: Replacing Glock Sights: https://www.nrafamily.org/content/hints-from-our-armorer-replacing-glock-sights/
- XS Sights, How to Install Glock Sights: https://xssights.com/blog/how-to-install-glock-sights-with-sight-pusher-tool-or-file-to-fit/