Best Holosun Shotgun Red Dot Sights PLUS How To Mount

Hey Freedom Gorillas today we're taking a deep dive into how to mount red dots on shotguns! If you’ve got a non-optics-ready shotgun and you’re wondering how to mount a red or green dot sight, you’re in the right place. This is our universal shotgun red dot fitment guide, built to help you pick the best Holosun optics for your setup—and walk you through three mounting methods you can use to get them on your shotgun.

Mounting a red dot to your shotgun is one of the smartest upgrades you can make—whether you're busting clays, defending your home, hunting turkeys, or setting up a tactical rig. Red dots give you faster target acquisition, better low-light performance, and a clear, single point of focus—no need to line up front and rear sights. That’s huge for anyone with aging eyes, or for those quick, high-pressure shots.

Some red dot reticles—like the Holosun 503G-ACSS—even act as a visual cheat sheet for your shot pattern, showing you a representation of where your buckshot is going to hit at 25 yards. That kind of precision makes all the difference.

So if your shotgun isn’t optics-ready, don’t worry—we’ve got you covered with the exact parts, mounts, and Holosun optics you’ll need to get it dialed in. Let’s jump into the three ways you can mount a red dot to your shotgun.

What This Guide Covers

Option 1: Rib Vent Mount

Option 2: Picatinny Mount

Option 3: Adapter Plates

In this universal shotgun red dot mounting guide, we’ll walk you through the three most common ways to mount a red dot to your shotgun—no gunsmith required.

There’s no one-size-fits-all solution when it comes to shotgun optics, but thankfully, these three methods cover just about every platform. Whether your shotgun has a vent rib barrel, a Picatinny rail, or is drilled and tapped, you’ve got solid options.

Each method has its own pros and ideal use cases, and we’ll break down the benefits, recommended Holosun optics, and the exact parts you’ll need to mount your red dot.

Mounting Method Summary Table

🔎 Not sure which one you need? We’ll help you identify your shotgun and set you up with the right red dot—just visit our Contact Page.

Option 1: Shotguns with Vent Rib Barrels

This will by far be the most popular and universal option to mount a red dot onto your shotgun. Field-style shotguns like the Mossberg 500 Field, Remington 870 Express, and others often have a vent rib barrel—a raised, slotted strip along the top of the barrel for heat dissipation and aiming.

While they don’t come optics-ready, you just need a clamp-on rib mount to make it happen.

Here's a quick video on how it works and how to install the mount:

Benefits of Vent Rib Mounts:

• Ultra-low bore height = more instinctive aiming
• Preserves your cheek weld
• Helps with faster follow-up shots
• Removable and reversible for multi-season use
• Installs directly onto the rib—no modifications or tools needed
  

Best Red Dots for Vented Rib Mounts

Pistol Optic Choices - Will Need This Mount - Pistol red dots are compact, lightweight, and sit lower to the bore—making them ideal for shotguns, especially those with vent rib mounts or minimalist builds. Their smaller footprint and shorter height help maintain a solid cheek weld and reduce bulk on top of your gun. Many pistol dots, like the Holosun 507C or EPS Carry, still offer multiple reticle options and enclosed emitters for durability. If you’re running a hunting setup or a Shockwave-style firearm, a pistol dot is a sleek, efficient choice that won’t throw off your balance or handling.

	This Warne mount is one you need to use if you'd like to use pistol optics. This will mounts a K footprint, RMR footprint, or DeltaPoint Pro footprint optic - listed below.
	407K / 507K - The 407K gives you a nice 6 MOA Dot which makes target acquisition easy. The 507K has a 32 MOA Ring with 2 MOA Dot for those who prefer that reticle. Needs this mount.
	EPS Carry or Full Size - These come with many different reticle options including a 2 MOA Dot only, 6 MOA Dot only, or 32 MOA Ring and 2 MOA Dot. The full size will obviously be a larger optic overall including a larger window.Needs this mount.
	407C / 507C - The 407C gives you a 2 MOA Dot which make this option an affordable budget optic. The 507C has a 32 MOA Ring with 2 MOA Dot for those who prefer that reticle.Needs this mount.
	507 COMP - This optic has multiple reticle option to pick from, but it also has Holosun's large window out of any pistol optic. Needs this mount.
	SCS 320 - This optic is an enclosed dot that uses the solar charging sight (SCS) technology so you never have to worry about batteries. Needs this mount.

Great Rifle Optic Red Dots - Will Need This Mount - Rifle optics have larger windows. A wider sight picture can help with faster transitions between multiple targets, and models like the Holosun 503G-ACSS even offer reticles that show your pattern spread at specific distances—a huge benefit for buckshot or slug users.

	If you'd instead like to mount rifle optics like the ones mentioned below, you will need this T1/T2 Warne mount instead.
	Holosun 503G-ACSS - Even though the 403/503 line is now discontinued, the 503G-ACSS is a collaboration with Primary Arms and will still be continued to be made. This would be my go to option for any shotgun because the ACSS reticle show you your shotgun pattern at 25 yards! Needs this mount.
	Holosun ARO - This optic replaced the 403 series as Holosun's new budget rifle optic. Now all ARO models have shake awake, different reticle options, and a 22mm window. Needs this mount.
	Holosun ARO-EVO - This optic replaces the 503 series and is the upgrade to the ARO line. These optics use a 26mm window, have solar failsafe, and are made of a more durable aluminum than the ARO line. Needs this mount.
	Holosun 515 Series- This optic series is the premium of the tube series. All models come with an anti-reflective device, lens covers, and premium quick disconnect mounts. Needs this mount.
	Holosun 530 Series- This optic series is the elite all the tube optics. It has a 30mm window and is made of titanium. All models come with an anti-reflective device, lens covers, and premium quick disconnect mounts. Needs this mount.

Option 2: Shotguns with a Picatinny Rail

If your shotgun has a factory-installed Picatinny rail on top of the receiver, congratulations—you’ve got the easiest setup to work with. Tactical shotguns, such as the Mossberg 500 ATI Tactical, Mossberg 590 SPX, or Remington 870 Tactical, often come with one out of the box.

Why It’s a Great Mounting Platform:

• Accepts nearly any red dot with a Picatinny base
• Easy to install and remove
• Compatible with both rifle and pistol optics (with additional low mount)
• No need for adapter plates or custom milling

Recommended Red Dots for Shotguns with Pic Rails

Rifle optics that come with the included low picatinny mount:

	Holosun 503G-ACSS - Even though the 403/503 line is now discontinued, the 503G-ACSS is a collaboration with Primary Arms and will still be continued to be made. This would be my go to option for any shotgun because the ACSS reticle show you your shotgun pattern at 25 yards!
	Holosun ARO - This optic replaced the 403 series as Holosun's new budget rifle optic. Now all ARO models have shake awake, different reticle options, and a 22mm window.
	Holosun ARO-EVO - This optic replaces the 503 series and is the upgrade to the ARO line. These optics use a 26mm window, have solar failsafe, and are made of a more durable aluminum than the ARO line.

Optics that will need an additional picatinny mount:

	509T - You will need this low mount. The 509T is an enclosed emitter with a housing made of titanium.
	SCRS - You will need this low mount. The SCRS is a small profile tube sight that has an internal rechargeable battery so you never have to worry about battery life.
	407K / 507K - You will need this low mount. The 407K gives you a nice 6 MOA Dot which makes target acquisition easy. The 507K has a 32 MOA Ring with 2 MOA Dot for those who prefer that reticle.
	EPS Carry or Full Size - You will need this low mount. These come with many different reticle options including a 2 MOA Dot only, 6 MOA Dot only, or 32 MOA Ring and 2 MOA Dot. The full size will obviously be a larger optic overall including a larger window.
	407C / 507C - You will need this low mount. The 407C gives you a 2 MOA Dot which make this option an affordable budget optic. The 507C has a 32 MOA Ring with 2 MOA Dot for those who prefer that reticle.
	507 COMP - You will need this low mount. This optic has multiple reticle option to pick from, but it also has Holosun's large window out of any pistol optic.
	SCS 320 - You will need this low mount. This optic is an enclosed dot that uses the solar charging sight (SCS) technology so you never have to worry about batteries.

This gives you the freedom to pick an optic based on your budget, shooting style, window size preference, and reticle choice—without worrying about adapter plates or footprint compatibility.

✅ Use a Low Pic Mount – Here's Why:

A key consideration when running a red dot on a shotgun is the height-over-bore. Most shotgun stocks don’t have adjustable combs or risers, meaning your eye naturally aligns lower when shouldering the gun. If you install your red dot on a tall mount, your cheek weld is gone—you’ll need to lift your head off the stock just to see the dot, which slows you down and breaks your consistency.

That’s why we strongly recommend using a low-profile Picatinny mount for your red dot. It keeps the sight closer to the bore and in line with your natural eye position, which:

• Keeps your cheek weld solid
• Improves target acquisition speed
• Helps reduce neck strain and missed shots

Look for “low mount” or “absolute co-witness” style mounts when shopping for your red dot. 

What If Your Shotgun Doesn’t Come with a Picatinny Rail?

No worries—if your shotgun is drilled and tapped (meaning it has four small screw holes on top of the receiver), you can easily add a Picatinny rail. These rails bolt directly into the receiver and give you the same optic-mounting capability as a factory tactical model.

At Freedom Gorilla, we carry precision-fit EGW rails for popular shotguns, so you can confidently mount any red dot using a low Picatinny mount.

Here’s a quick guide to which rail you’ll need:

Once your rail is installed, you’ll be able to use any low-mounted red dots from the list we shared above.

Option 3: Adapter Plates for Drilled & Tapped Shotguns

If your shotgun is drilled and tapped, but you’d rather skip the bulk of a Picatinny rail, there’s another clean solution: adapter plates.

These plates screw directly into the receiver and let you mount a red dot without a rail. That means lower profile, lighter weight, and is ideal for those who want a sleeker setup.

Adapter plates are shotgun model-specific and designed to match your receiver’s curvature and screw spacing. Once installed, they give you a direct-mount footprint—usually RMR, K Series, or both—allowing you to choose from a wide range of optics.

Shotgun Adapter Plate Fitment Guide

Here are the shotgun models we support with direct-mount adapter plates and the footprints they’re compatible with:

RMR Footprint Optic Selection

	407C / 507C - The 407C gives you a 2 MOA Dot which make this option an affordable budget optic. The 507C has a 32 MOA Ring with 2 MOA Dot for those who prefer that reticle.
	507 COMP - This optic has multiple reticle option to pick from, but it also has Holosun's large window out of any pistol optic.
	508T - This optic is made of titanium instead of aluminum and has a larger and flatter window than the 407C/507C.

K Footprint Optic Selection

	407K / 507K - The 407K gives you a nice 6 MOA Dot which makes target acquisition easy. The 507K has a 32 MOA Ring with 2 MOA Dot for those who prefer that reticle.
	EPS Carry or Full Size - These come with many different reticle options including a 2 MOA Dot only, 6 MOA Dot only, or 32 MOA Ring and 2 MOA Dot. The full size will obviously be a larger optic overall including a larger window.
	SCS Carry - This is an enclosed option similar to the EPS Carry. This utilizes the solar charging sight (SCS) technology. It has an internal battery that recharges. This is a pure set-it-and-forget-it option.

Not Sure Which Style Shotgun You Have?

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Final Thoughts

No matter which shotgun you run, there’s a reliable way to mount a red dot—without permanent modifications. Whether you’re protecting your home, chasing gobblers, or shooting clays, the right optic makes a big difference in speed and accuracy.