Want to Add an Optic to Your Glock? Here Are Some Things to Consider

Red dot sights on handguns have exploded in popularity over the past few years, and for good reason. They make it faster to acquire your target, easier to shoot accurately, and can significantly improve your performance in everything from competition shooting to concealed carry. If you're thinking about adding an optic to your Glock—or any handgun—there are three critical things you need to understand before you buy.

1. Understanding Footprints

Here's where things get confusing for newcomers: not all optics fit on all guns. The term "footprint" refers to the pattern of mounting holes on the bottom of the optic. Think of it like different phone chargers—just because something's a red dot doesn't mean it'll fit your slide.

Common Footprints

RMR Footprint (Trijicon) is one of the most popular patterns. Originally designed for the Trijicon RMR (Ruggedized Miniature Reflex), many manufacturers now make optics compatible with this footprint. If your Glock slide is milled for an RMR, you have the most options available.

RMSc Footprint (Shield) is a smaller footprint designed for compact and subcompact pistols. It's commonly found on smaller Glocks like the G43X and G48.

Holosun K Series Footprint has become increasingly popular and some manufacturers are adopting it as a standard. It's slightly different from the RMR pattern.

Direct Mount MOS Plates come with Glock MOS (Modular Optic System) models. Glock includes adapter plates that let you mount various optic footprints. However, many shooters upgrade to aftermarket plates for a more secure fit.

Glock-Specific Considerations

If you have a Glock MOS model (like the G19 MOS, G17 MOS, etc.), it comes with multiple mounting plates from the factory. These plates allow you to mount different optic footprints. However, the factory plates sit higher than direct mounting, and some shooters report they can loosen over time.

If you have a standard Glock (non-MOS), you'll need to either send your slide out for milling or buy an aftermarket optics-ready slide. Milling services cut your slide to accept a specific footprint. This creates a lower, more secure mount but commits you to one footprint pattern.

Pro Tip: Before buying an optic, confirm what footprint your slide accepts. If you're buying a non-MOS Glock and planning to mill it, research which footprint gives you the most optic options for your budget.

2. Closed Emitter vs. Open Emitter

This is the second major decision you'll face, and it significantly impacts how your optic performs in real-world conditions.

Open Emitter Optics

Open emitter designs have the LED emitter exposed at the top or front of the sight. The classic example is the Trijicon RMR.

Advantages:

• Larger sight window provides better situational awareness
• Easier to find the dot quickly when drawing
• Generally more affordable
• Lighter weight

Disadvantages:

• Lens can get dirty, wet, or covered with snow/debris
• Emitter exposed to elements and potential damage
• Requires more frequent cleaning in harsh conditions

Closed Emitter Optics

Closed emitter designs (sometimes called "enclosed emitters") seal the emitter inside the housing. Examples include the Trijicon SRO and Holosun EPS series.

Advantages:

• Protected from dirt, rain, and debris
• Emitter won't get blocked or damaged
• Better for duty/carry guns in harsh environments
• More reliable in adverse conditions

Disadvantages:

• Smaller sight window in some models
• Often more expensive
• Slightly heavier

Which Should You Choose?

For competition shooting, many prefer open emitters for the larger sight window and lighter weight. The controlled environment of a range means weather isn't a concern.

For concealed carry or duty use, closed emitters offer more reliability. Your defensive gun needs to work when you need it most, regardless of conditions.

For general range use, either works fine. Choose based on your budget and preferences.

Many experienced shooters recommend starting with a quality open emitter to learn the platform, then deciding if you need the extra protection of a closed design.

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3. Do You Want to Co-Witness?

Co-witnessing refers to the ability to see your iron sights through or around your optic. This seems like a simple question, but the answer depends on your intended use and mounting height.

Types of Co-Witness

Lower 1/3 Co-Witness means your iron sights appear in the lower third of your optic window. You can see both the dot and your irons simultaneously. This is the most common setup on handguns.

Absolute Co-Witness means your iron sights line up exactly with your red dot. Both sit at the same height. This is rare on handguns but common on rifles.

No Co-Witness means you can't see your iron sights through the optic at all. This happens when the optic sits very low or you've removed your iron sights entirely.

Should You Keep Your Iron Sights?

This debate gets heated in the gun community. Here's both sides:

Keep them:

• Backup if your optic fails or battery dies
• Helps during the transition period while learning the dot
• No real downside to having them
• Many instructors recommend keeping irons on carry guns

Remove them:

• Cleaner sight picture
• Less clutter in the window
• Modern optics are reliable enough
• Forces you to trust and learn the dot
• Slightly reduces weight

For Glock specifically, most shooters keep their factory sights when first starting with an optic. The Glock iron sights are low-profile and don't obstruct much of the window. You can always remove them later if you decide you don't need them.

Important Note: Even with co-witnessed irons, you should regularly check your optic's battery and keep a spare. Most modern red dots last 1-2 years on a single battery, but checking it should be part of your routine maintenance.

Installation Tips

If you have a Glock MOS:

1. Clean the mounting surface thoroughly
2. Install the correct adapter plate (if needed)
3. Apply a small amount of thread locker to mounting screws
4. Tighten screws in a cross pattern to manufacturer specs
5. Consider upgrading to aftermarket plates (CHPWS, Forward Controls Design) for a more secure mount

If you're having your slide milled:

1. Choose a reputable gunsmith or milling service
2. Decide on footprint before sending it out
3. Consider having them add front serrations while they have it (popular upgrade)
4. Expect 2-4 week turnaround times
5. Budget $75-150 for quality milling work

Learning to Shoot With a Red Dot

Adding an optic is just the first step—you need to learn how to use it effectively:

Focus on the target, not the dot. This is the biggest mistake new shooters make. Keep your focus downrange and let the dot appear in your vision.

Practice your draw stroke. You need to present the gun consistently so the dot appears in the same place every time.

Start close and slow. Begin at 5-7 yards and focus on fundamentals. Speed will come with practice.

Dry fire regularly. Practice presenting the gun and finding the dot without live ammunition.

Be patient with yourself. Most shooters take 500-1,000 rounds to feel comfortable with an optic. It's worth it.

Battery Management

Unlike rifle optics, pistol red dots typically use smaller batteries:

• RMR and similar use CR2032 batteries (very common)
• Some models use CR1632 batteries
• Battery life ranges from 1-4 years depending on model and settings

Best practices:

• Change batteries annually regardless of whether they're dead
• Keep spare batteries in your range bag
• Some optics have auto-shutoff features to extend battery life
• Consider models with side-loading batteries so you don't lose zero during changes

Final Thoughts

Adding an optic to your Glock can transform your shooting experience, but it requires careful consideration of footprint compatibility, emitter type, and sight configuration. Take your time researching which combination works best for your needs and budget.

Once installed, commit to training with it. The learning curve is real, but thousands of shooters have proven that red dot pistols offer significant advantages in speed and accuracy. Whether you're carrying, competing, or just having fun at the range, a properly set up optic is a worthwhile investment.

Remember: the best optic is the one you'll actually train with. Don't get paralyzed by options—make an informed choice and get to the range!