If you haven’t already had the experience of looking down the slide of an optics-ready pistol that is topped with a micro red dot, you’re behind the times. There’s nothing faster for target acquisition. Simply find the red dot on your target and pull the trigger.

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The old-school front-sight/rear-sight alignment paradigm that defines most all handguns is fast enough for those who train regularly and who learn the complexities of the skill set. But even those shooters find good red dot optics speed things up. So what do you need to do to put a red dot on a pistol?

We’ll parse it out. But first, let’s talk a bit of philosophy.

Bigger dots are easier to find fast. Small dots offer more potential for accuracy. Either way, a red dot, like this AT3 ARO, is faster than irons.

Why go Optics-Ready?

A word on the “why” of this concept. Optics-ready pistols still have traditional iron sights. While there’s a slight increase in the price of production–a cost that is often passed on to the consumer–the additional milling and preparation gives you options. If years down the line, you decide you want to top your GLOCK or Smith & Wesson or whichever gun, you’ll have the options right there.

What if you already have a gun, though, and it isn’t ready for a red dot?

Getting an optic on a pistol is easy if the slide has been designed to accept red dots from the factory. If not, a gunsmith can help.

The Gunsmith

There’s always one old-school option for getting an optic on a pistol. Let’s say you have an old 1911 that is not optics ready and you want to change that. Take it to a competent gunsmith.

The gun will never be the same. And if it is a valuable piece before it goes in, it will lose some of that value coming out. But you will gain the functionality that comes from milling a slide to accept an optic.

Just know that the change is permanent. There are few options for red dots–very few–that don’t require an alteration to the slide. And, unless you have a really good gunsmith, there may not be a cover plate that would preserve the aesthetics of the original slide.

The finish may vary in color, or serrations may not carry onto the plate. While this is hardly the end of the world, and a moot point if you are ready to mount a red dot, it is still something to consider.

The extra protrusion up top is still very easy to conceal. You will need to have a holster that allows for the optic, though.

Optics Ready Pistols

When we say “optics ready,” the insinuation is that the gun is coming from the factory with the ability to accept optics. This typically entails a small section of the slide–just ahead of the rear sight–being milled off to a depth of about 1/8″ +/-.

A cover plate will attach to the milled slot. This is typically done with a small pair of hex bolts. When you remove the plate, you can mount a red dot directly to the slide or you can add an adapter plate that will allow you to add a red dot (it all depends on the pattern milled into the slide and its compatibility with available optics).

Some optics-ready pistols build in higher sights so that the irons and red dot will co-witness. Others, like this GLOCK, don’t.

Optics Ready from the factory

Many companies have caught on to this trend. Almost all of them, in fact. What used to be a boutique add-on customization is now standard. Even the old classic designs are being modified to accept red dots and micro red dots.

Most work to make a generic slide cut with modular adapter plates. Some companies will include these plates in the box with a factory gun, others see the opportunity to sell them as add-ons. This reflects the diversity of options available.

And it makes sense, really. Most optics will mount to one of four plate styles, but few of us need more than one. Most, I find, pick a brand or a pattern and stick within that mounting style.

The Naming Conventions

Optics mount names are hard to decipher. Each one has a name that is associated with the designer or the original red dot that was intended to be used on that plate. This, though, gets esoteric.

The way most of us talk about the plates is by naming them after the most popular red dot style that mounts to it. This is much easier to decipher, really, as the names are more common to the industry and there’s not so much mystery behind them.


The Docter pattern has two holes for mounting screws. On each of the four corners are sockets that hold alignment pins. It is easy to attach and reliably stable.

As this is a solid mount, it is one of the most widely used. The four pins make this exceptionally stable and resistant to stresses from the front and rear (as is common when a slide cycles) and from the sides (like might happen as you holster your gun).

Most know this pattern because some of the Burris and Vortex red dots use this pattern to connect (the pattern is also commonly referred to as “Burris/Vortex pattern”). This is also the pattern AT3 chose for its ARO Micro Red Dot.

The AT3 ARO is ideal for compact and duty-sized handguns, and it works just as well on shotguns and rifles. And because the Docter pattern is used so widely, adapter plates are very easy to find.

The C-More Standard

The C-More Standard mount pattern uses two holes for mounting screws and just two pins for alignment. Even so, the mounts are robust and can handle the recoil without shifting. Some of this strength comes from the size of the pins that align the sight to adapter plates.

Sig uses C-More, as does Vortex and Leupold. It is really quite simple in its design. While this is another of the trusted options, it has yet to catch on like some of the others.

There’s a lesson in that. Each time a new mount or pattern hits the scene, companies have to decide to adopt or not. M-LOK is a great example. It seems to have staying power, while other accessory mount types languish. And the more companies adopt the design, the more accessories will be made for it, and the more it will become a standard.

The Shield RMSc

The Shield RMSc pattern is used by Shield, Holosun, Leupold, Riton, and even Sig.  This is one of the most compact of the plate designs, which has made it popular for many new entrants into the Micro Reflex Sight market.

The Shield RMSc pattern is ideal for micro-compact pistols, where real estate is a limiting factor. In a way, it is like a downsized Doctor–four pinholes, two mounting screws.

As many companies now make micro-nines, this has become another mount pattern adopted by multiple companies.

The Trijicon RMR Standard

Trijicon is a major player in optics, and the pattern for the RMR has become a go-to for many in the industry. The RMR plates will have two screws and to pins in the front corners.

While this two-pin/two-screw design is similar to the C-More, the spacing is different.

The plate design is commonly used by Trijicon, of course, Holosun, and others.

Optics Ready Takeaway

The big picture for mounting plates is simple: versatility is key. Almost all of the optics-ready designs that come from gun makers are milled out to accept various adapter plates. This is a money-making add-on for some companies, while others will include two or three of the most common plates in the box with the gun.

The best way to know what you should look for is to understand which optic you want to run. Once you make that call, determining which mounting adapter you’ll need (if any) can be done with a simple search.

One Last Tip

If there’s anyone that knows the AR-15 platform, it’s the US military. As a special offer for our readers, you can get the Official US Army Manual for AR-15/M4/M16 right now – for free. Click here to snag a copy.

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5 thoughts on “The Optics-Ready Pistol Bible

  1. I have the AT3 ARO and need an adapter for a Glock 19 gen 3 rmr footprint ! Can you assist me ?

    1. Hello James!

      This is a tough one. If I am understanding you correctly you are saying that your slide has an RMR cut and you also have an ARO which has a Doctor style footprint. In this case there is very very little in the way on an adapter. We don’t stock any because there is such a small pool of options as well as quality or simple options (or we just plain can’t get them). There are some out there on Amazon for example that we would not recommend. They just do not look to be up to par.

      However the team and I did some looking and found the Rival Arms Slide Mounted Optics Adapter Plate – Trijicon RMR to Docter (SKU:RA45R001A). Though this is an item we will probably never stock it looks to be one of very few actual adapters out there. It seems to have some strange screw/spanner setup but it would not be the worst thing to look into further.

      I hope this was of some help. Safe shooting!

  2. I recently purchased a Walther PDP Compact 4, which included in the box a card allowing me to request one of four optics plates (Docter, Trijicon RMR, Leupold DPP, and Vortex Viper). Which of these mounting options would your AT3 ARO red dot sight fit?

  3. Really a good read ,do you have any info on the pt809 tarus?

    1. Hi Mike, what info are you interested in? After a quick search it doesn’t appear the Taurus PT809 has an optics-ready option.

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