Comparison of two smallest red dots on the market: Shield RMSsc and Sightmark A-Spec M3

More and more compact and subcompact handguns are now being manufactured with slide cuts tailored for specific red dot footprints—most commonly the Shield RMSc footprint. Here, we’re comparing two red dot sights that use this popular footprint and stand out as some of the smallest in their class.

Side note: We’re big fans of direct-mount red dots on subcompact pistols. While full-size handguns benefit from flexibility in choosing various optics and footprints, tiny pistols are naturally limited to only the smallest red dots—so a dedicated footprint just makes sense.

First things first—both of the optics we’re covering here use the Shield RMSc footprint. That means they can be directly mounted on a wide range of pistols with an RMSc cut from the factory (e.g., Glock 43X MOS, CZ P-09 Nocturne, CZ Shadow 2 Carry, and many others).

And since size does matter—at least in the world of optics as we understand it—we’re putting two of the smallest red dots head to head: the Shield RMSsc and the Sightmark Mini Shot A-Spec M3 Micro Reflex Sight.

Quick tip for @Sightmark: maybe consider naming your subcompact red dot something more... subcompact? 

Video

In case you do not like to read (its quick article though!), I put my video straight here below.

Personal tip from me: You can skip the unboxing unless you await your red dot little too much. If you go to 1:30, you will get to the important and useful info straight away.  

Key differences

What makes these two different that may not be visible on the first sight? 

Dimensions

They are both extremely small, but each of them in different way:

Shield RMSsc dimensions:

• 40.8 mm long,
• 19 mm wide and
• 21.5 mm high. 

Weight of Shield is 16.1 g [0.56 oz].

Sightmark Mini Shot A-Spec M3 dimensions: 

• 40.8 mm long,
• 23 mm thick and
• 22.8mm high.

Weight of Sightmark is 20 g [0.7 oz].

So altogether, the Shield sight comes out as a slightly smaller and lighter of those two.

Red dot size [MOA dot] 

Shield RMSc is availalbe in two variants - 4 MOA dot and 8 MOA dot. Given the idea behind subcompact pistols is mainly self defense, the 8 MOA dot option is very practical.

The Sightmark comes from production only with 3 MOA dot. 

Both only offer red color for the dot [i.e. not green].

Battery life expectancy

Battery life comes from the battery foremostly, but it is very different numbers, so it is definitely worth mentioning:

Shield's battery is expected to last cca 9 000 hours in average daylight.

Sightmark's battery has life expectancy between 500 and 100 000 hours [heavily depends on the ambient light settings].

Picatinny mount included / not included 

Both of these red dots are made for pistols primarily, given its size. Despite that, Sightmark includes also Picatinny mount, making sure you can use this red dot even on guns equipped with Picatinny base. 

Shield on the other side does not include such mount together with the red dot. You can still install the red dot on Picatinny, but you will have to buy the Picatinny mount extra (for example here).

Water resistance

We dont expect you to play James Bond role and be fighting in Venice on boat with neither of these, but still something worth mentioning - the Shield has more solid IP67 rating and is more water resistant compared to the Sightmark with IP55 score. 

Basic controls

There are no contorls on neither of the optics. The only thing you can change is windage and elevation. 

Brightness gets adjusted automatically based on the light conditions, and both of the optics only use 1 reticle. So there is not much to control anyway. 

Other notes

Both of these sights use batter insertion from the bottom. In other words, you will have to put the sight down in order to switch battery. Given the simplicity of both of the optics, it makes sense for me.

Shield uses CR1632 battery (despite claiming its CR2016 battery).

The Sightmark uses CR2032 battery.

How to install these optics to your gun?

If your gun is optics ready and has Shield RMSc cut in the slide, you do not need anything except of just the red dot.

If your pistol is classic Optics Ready vairant, that needs to use red dot plate, you need to get such. For both of these you will need then optics ready plate that uses Shield RMSc footprint. 

And in case you have classic model without any optics ready cuts whatsover, you will need to search for red dot mount with Shield RMSc footprint instead. We have plenty of those too.