Griffin Armament’s Mk 2 AR Pistol: Big Power, Small Package

Images by the author unless otherwise noted

*Disclaimer: Griffin Armament sent the gun, the suppressor, and two optics. They did not go back.

To many readers, products from Griffin Armament (GA) are not news. The company, located in Watertown, Wisconsin, has long been known for its optics, firearm parts, suppressors (I reviewed a couple of GA suppressors on this site, here), and complete firearms. This review is about one of those complete firearms, a Mk 2 AR pistol, and they included a suppressor (link below) and a couple of their optics to round things out. Those optics included a Griffin Multi-Reticle Emitter (MRE™) red dot and a Heads-Up prism sight. I’ll explore these a bit further down. 

Back to the rifles…. 

GA makes a lot of AR-style rifles, pistols, lowers, and uppers. Here are their lines…

• Mk 1
• Mk 2
• Mk 2 AR9 9mm

In addition, they make lowers in three calibers: 5.56mm, .300 Blackout, and 9mm. You can also buy a complete upper to finalize your build in 5.56mm and .300 Blackout. There are too many options to list here. They also sent an HRT5K Dual-Lock suppressor… more on that later. (They call them “silencers”, just like Hollywood!)

Differences… Mk 1 and Mk 2

I did some digging online and came up with the following differences between their older Mk 1 rifles and the newer Mk 2… the following is from Wikipedia and summarizes those differences:

Lower Receiver & Ergonomics

MK1: Utilizes standard, non-ambidextrous controls, offering a traditional AR-15 layout.

MK2: Features a fully ambidextrous lower receiver machined from custom-forged 7075-T6 aluminum. It includes ambi bolt catch/release, ambi magazine release, and an ambi safety selector.

Upper Receiver & Rail

MK1: Traditional fit between the handguard and the upper receiver.

MK2: Features an anti-rotation tabbed interface where the rail locks securely into the upper receiver. This eliminates handguard flex and maintains perfect zero for mounted lasers and optics.

Internals & Gas System

MK1: Standard internal components and buffer systems depending on the specific model.

MK2: Comes with the Griffin Enhanced BCG, pinned Primo Gas Block, and the AR-SOB (Suppressor Optimized Buffer) to provide a smoother shooting cycle when running suppressors.

Hardware & Muzzle Devices

MK1: Typically equipped with older legacy Griffin mounts.

MK2: Outfitted for Griffin’s Dual-Lok suppressor mounting systems and ships with their Gen 2 SN-ACH (Suppressor Optimized Charging Handle) for reduced gas blowback. 

If you are trying to decide between the two, the MK2 offers premium front-line fighting features out of the box (like full ambidexterity and rigidity), while the MK1 serves as a high-quality but more traditional base rifle.

This Gun

This Mk 2 pistol has some features that I like… I list some here and also some others at the bottom. They include:

1. Barrel

First of all, it has a 12.5-inch barrel. I have another AR pistol in 5.56mm that uses a 9.5-inch tube, but I like the slight bump in velocities that you get with three additional inches. (I’ll skip the various jokes.) I can’t really feel a difference in handling… the shorter-barreled gun has an integral suppressor that adds some weight, while this GA pistol’s 3D-printed suppressor is of the screw-on variety and is lighter. So, it’s about a wash in terms of each gun’s total weight and overall length, but as I said, I’ll take a few more FPS every time with all else being equal. I do notice that my other, integrally suppressed AR is more muzzle-heavy than this GA pistol, but again, that’s to be expected due to the built-in machined metal suppressor that the barrel ends with.

2. Ambidextrous Lower

Next, we have a lower that is totally ambidextrous, a feature near and dear to my left-handed heart. I just got used to flipping the safety on right-handed ARs over the years, and with this one, I don’t have to do that. I also like that lever, as it is textured differently from any other AR safety I’ve seen to date. 

3. Picatinny Rail

Every AR that I’ve seen uses a Pic rail on at least a portion of the receiver/barrel. This one goes to the muzzle, a feature I don’t often see. You have a full-length rail that allows you to add whatever optic you desire.

4. 223 Wylde Chamber

I am very glad to see that they incorporated the Wylde chamber in this gun, and in almost AR they build. Why does it matter? To put it succinctly, you get the best of the civilian .223 and the military 5.56mm chambers together in one. The problem comes in trying to shoot 5.56mm ammo in a .223 chamber. Military 5.56mm ammo is loaded a bit hotter than civilian .223. Being a reloader, I’m familiar with two different sections in loading manuals. One is for 223, and the other for 5.56, with loading data a bit different for each. The other issue concerns each cartridge’s respective chambers. 

There is a difference between the two. The chambers are cut differently, in a nutshell. The civilian 223 chamber is tighter, with a shorter freebore (leade, or throat). The military 5.56 chamber has a slightly longer leade. Shooting 5.56 in a 223 chamber can lead to split cases, although that is rare. That makes the Wylde chamber desirable, as it combines features from both chambers and allows both types of ammo to be shot.

This diagram I got from gundigest.com helps explain things visually:

Lastly, here is a short video that helps explain the Wylde chamber.

Why should you consider getting a rifle so chambered? Two reasons. First, you can safely shoot both civilian .223 and military 5.56mm rounds in the same chamber, and secondly, your accuracy generally improves with both cartridges as your rifle’s chamber isn’t a compromise but is cut to take advantage of both cartridges’ accuracy potential. 

Those are four excellent points to consider about this pistol.

Here are some photos I took, both inside and outside…

Here we see the forward hand guard with the front fold-down sight and Viridian’s new 4K DUO light/laser handgrip. I recently reviewed that light – you can read it here. This light favors those who like to wrap their support thumb over the top of the Pic rail.

Another option would be a vertical foregrip – I use those, as well. Case in point: I stuck a $55 HiLight Tactical TGBL20 vertical foregrip on, after the Viridian. I’m not sure which one will stay. They both perform a dual function and are handy. The one main advantage that the vertical grip offers is that it functions as another way to pick the gun up. That can be useful.

Below is the handguard that comes on the gun:

Nothing wrong with it; I just had the Viridian come in for review, and I wanted to mount it on something that I’d use a lot.

More photos…

The prism and folded-down rear aperture sights. I love the folding lens covers.

Here we have a close-up of the safety lever. I like the texturing… It’s easy to find with your thumb. Also, don’t believe that “auto” marking… it ain’t necessarily so!

A shot of the ambi controls. They work without requiring major effort. Above is the right side, and below, the left. 

The easily adjustable arm brace.

Features & Specifications

• Compressor-Optimized Buffer System
• Griffin 416R SS HEDP™ Barrels
• Griffin Enhanced BCG
• Griffin Forged Upper And Lower Type 3 Hardcoat Anodized
• Anti-rotation tabbed rail locks into the upper
• Full-length Picatinny rail
• Griffin Full Ambidextrous Lower w/ 60-degree Flared Magazine Well and Integrated Trigger Guard
• Ambidextrous Features: Magazine Release, Bolt Release & Catch, Safety Selector Kit,  and SN-ACH™ Gen 2 Charging Handle
• Griffin A3 Grip
• Griffin Enhanced Trigger Guard
• Griffin Contour Connect QD End plate
• Griffin Maritime Receiver Extension™
• Griffin AR-SOB (Suppressor Optimized Buffer)
• SBA3 Pistol Brace
• Griffin RailShield™ 4 Piece Panel Kit
• Griffin Low Pro Rail System
• Griffin Primo Gas Block (pinned)
• Griffin Silencer Mount Muzzle Device
• Griffin Dimpled Takedown Pins
• Weight: 6lbs. 5oz.
• Overall Collapsed Length: 29″
• Magazine Included: Yes, 30-round
• Warranty Limited Lifetime
• MSRP  $1459.95

Looking at the gas system and barrel specifically, we get this from the gun’s web page:

The MK2 CQB 12.5″ 223W pistol is a quality shorty. The tuned mid-length gas system and suppressor-optimized buffer system ensure a soft yet reliable gas system, suppressed or unsuppressed. The 416R SS barrel provides exceptional accuracy and durability. We ran one of these barrels to 47,000 rounds, 100% suppressed while test firing suppressors with zero baffle strikes, and the rifling was still present. The barrel was retired due to extension lug wear, not due to barrel rifling wear. Other case studies, such as multiple M24 SWS barrels holding 0.35 MOA to 20,000+ rounds in army testing, provide further evidence that 416R SS is an extremely durable barrel material.

Now, let’s look at the other items they sent: the suppressor and two optics.

The HRT5K Dual-Lock suppressor is, as I said above is 3D printed via the DMLS additive manufacturing technology.

It is made from nickel 625X powder. I like the fact that they claim left-handed shooters benefit from this lower-back-pressure model… I did not experience much gas blow-back, so I guess it works. Another claim is that the nickel powder they use has a +/- 68% increase in yield and tensile strength over additively manufactured INCONEL® 625 at 1200°F. Inconel is a material found in many suppressors. I truly liked its smaller footprint and weight. You might not even notice it once it’s mounted on your rifle. Plus, there are no barrel length restrictions with this suppressor. 

The unique Hub mounting system allows for quick swapping between GA suppressors.

Features

• HUB-Compatible (1.375×24) Threaded Rear
• Ultra Low Backpressure Baffle System
• Additive Manufactured
• Minimal Size & Weight
• Ultra-Durable Nickel 625X™ Alloy Construction
• Printed Core Laser-Welded to Machined Rear for Warranty Serviceability
• Low Backpressure Flash Hider End Cap
• Highly Accurate with Minimal POI Shift
• Perpetual Lifetime Warranty™
• Here is some more information…
• Weight 11.5 oz
• Dimensions 4.51 × 1.5 × 1.5 in
• Material 17-4 H900 Stainless Steel, Nickel 625X™
• Suppressor Type  Hard Use, Low Backpressure, Rifle, Tactical
• dB Rating -34.7dB (137.3dB on 12.5″ MK2)
• User Serviceable  No
• Full Auto Rated Yes
• Mounting System HUB (1.375×24)
• Distance to Blast Baffle from Rear of Blind HUB Interface 1.50″
• Caliber .22cal (5.56mm)
• MSRP: $684.95

If you are in the market for a can for your 5.56, this one works well.

Now, the optics.

Multi-Reticle Emitter Red Dot

Image: griffinarmament.com

For those hunting for a small and light red dot, this is one to consider. It is the smallest and lightest one that GA makes and, as such, is in demand. It is useful in almost every situation… it can be mounted on pistols, carbines, or rifles (with a separate mount, such as the GA RTO™ Offset Plates – Trijicon RMR Footprint) as it features an RMR footprint. Another mounting option for long guns is the set of QD mounts that GA makes. You can get these in various heights… I have used one with one of my ARs for a good while. So we see that this red dot is very versatile.

Here are some of its features…

• Choice between Red or Green Reticle
• Selectable Ring/Dot Reticle
• 1 MOA Adjustment Increment
• 10 Brightness Settings (2 NV)
• Parallax Free – 25yds
• Auto-Off Battery Saver (4-hour auto-off)
• RMR Footprint
• Shockproof (1500 Gs)
• Waterproof (IPX7)
• 50,000-Hour Battery Life
• Included Low Picatinny Mount
• Perpetual Lifetime Warranty™ (2 Years on Electronics)
• And its tech specs…
• Length: 1.95″
• Width: 1.61″
• Height: 1.36″
• Weight: 3.0oz
• Window Size: 26x22mm
• Lens Coat: Clear Multi-Coat Glass
• Max Elev Adjustment: 90 MOA
• Max Windage Adjustment: 90 MOA 
• MSRP: $238.95

This sight is very fast into action… my son appropriated it to add to one of his steel challenge guns. You select your reticle (dot, circle, circle/dot) via an up-arrow press and turn the unit off and on via a down-arrow press. 

GHS-R Heads-Up Prism Sight

I seem to be drawn to two basic optics for my long guns. I need to emphatically state that I am not a long-distance shooter. I have neither the skills nor room to engage in that end of our hobby, although I greatly admire those who can shoot the nuts off a gnat at 500 yards… their skill level amazes me. I am more of the backyard-range, deer-woods hunting type of shooter, where a long shot might be 150 yards… actually, the last deer I took was at a measured 149 yards. That’s not that far out there in terms of longer distances, but it’s considered a decently-out-there range at what we encounter at the junction of woods and corn or bean fields.

For that reason, I am drawn to two types of optics, as I just mentioned. In terms of scopes, I like those of the LPVO variety… low power variable optic. I’m good if my scope dial reads 1x-8x-10x and has a 24-28 mm objective lens. Of course, I own scopes in the 3x-9x or higher magnification range that utilize 40mm or greater objective lenses – I own a few of those – but I prefer short and light FFP scopes for my ARs and bolt guns meant to take deer in our woods.

I have also discovered prism optics. This type of scope can be made much shorter and lighter than what I call “traditional” scopes because of their use of prisms to fold the light coming in. I recently reviewed another GA prism scope, a GPS3XR – you can read that here. That review might make a good place to start if you are not familiar with the science behind prism scopes… I dug into the topic a bit. This GHS heads-up scope is similar in nature and works pretty much the same way. (The “R” in the model name denotes a red dot… You can also get it with a green dot.)

They call it a “heads-up” model because it uses a large window and can co-witness with the iron sights that come on the Mk 2. You don’t need to squint to see it with both eyes open.

One advantage of using their brand of sight is that it is designed to co-witness with the irons that come on the gun. Once you have the prism zeroed, lift up on the front and rear sights to have dual-sighting capability. Or, remove the irons if you like. It’s your choice, although having a set of back-up sights is not a bad thing.

Features & Specifications

Features:

• 3 MOA Dot Reticle
• 1 MOA Adjustment Increments
• 10 Brightness Settings (8 Daytime, 2 Night)
• Parallax Set at 25 yds
• Flip-Up Plastic Lens Covers
• Integrated Picatinny Mount (Co-Witness Height)
• Shockproof (1200 Gs)
• Waterproof (IPX7 – 1 meter for 30 mins)
• Fogproof Internals
• 8 Hour Auto-Rest with Shake Awake
• 50,000 Hours of Battery Life at Level 1 | 20,000 hours at Level 6 | 1200 hours at Level 10
• Perpetual Lifetime Warranty™ (2 Years on Electronics)

Specifications

• Magnification: 1x
• Window Size: 38x28mm
• Lens: Multi-Coated Glass
• Dot Size: 3 MOA
• Adjustment Increment: 1 MOA
• Max Elevation Adjustment: 90 MOA
• Max Windage Adjustment: 90 MOA
• Battery Type: (1) CR123A – Included
• Brightness Settings: 10 Levels (8 Daytime, 2 NV)
• Weight: 12 oz
• Dimensions: 3.00″L x 2.00″W x 3.00″H
• MSRP: $386.95

I want to mention four of the features listed about this GA prism scope, although all of them are very useful. These four really help me to do my best shooting…

1. The 3 MOA dot has 10 brightness levels available, 8 for day and 2 for darker conditions. Sometimes you need a very bright dot, and sometimes you don’t.
2. The lens caps flip up and lie flat on top of the scope. That is so helpful… I never know what to do with those detachable lens covers. I usually leave them at home or have even taped them to the scope body to dangle. With these caps, you’re covered… a fingernail “pop”, and they’re flat on top of the scope. Every manufacturer should adopt this system.
3. The scope is shockproof and waterproof. This Mk 2 slid down when I was storing it and plopped fairly hard on a wooden floor, but the sight was not affected.
4. Shake-Awake. This is a common feature, but I like it. The scope shuts itself off after inactivity and then wakes back up with motion. This is a nice feature for those who forget to hold the down arrow long enough to turn the sight off.

If you have not tried a prism sight, you might want to do so. They are very short and light, and they tend to work well if you like a dot reticle.

Observations

I noticed a few things about this pistol.

First, it was lighter than other similar guns I’ve fired, even with its 12.5-inch barrel. I mentioned above the 9.5-inch AR pistol I own, the one that is integrally suppressed, and how it seems a bit muzzle-heavier than this one. Both have their place, but for carrying around, I’ll take a lighter gun every time.

Secondly, the gas system was tuned for suppressor use. Being a lefty, I sometimes get blowback that right-handed shooters don’t get. I am no scientist, so I can’t really explain it, but I know that it happens. It doesn’t happen here, at least with the suppressor that came with the gun. I like that.

Third, the arm brace and strap are easily adjusted. I know that’s a picky thing, but I’ve had some ARs that you almost have to wrestle with the stock or brace to get it to slide open or closed.

Lastly, you get iron sights on the gun and a 30-round magazine right out of the box. These two items are not really big deals, but they do help – especially if you are not able to immediately mount an optic. You wouldn’t believe how many ARs I see in my writing that do not include one or the other (or both) of these items.

Shooting The Mk 2

A seriously messy bench, for sure… I was in a hurry as usual and just tossed the stuff on my newly located bench. Two items I always use are the Athlon chronograph and the Caldwell Brass Trap (well, the Trap with anything but revolvers). They are used on just about every visit to my benches. Plus, you can see the duct tape over the Birchwood Casey shooting bag… I thank a Charter Arms 9mm revolver for that…

Since this is technically an AR pistol, I don’t shoot that breed of gun at the longer distances that I usually shoot full-length carbines or rifles at. I usually start at around 25 yards to make sure everything is dialed in, optics and zero set, and then may move back to 50 yards. That’s what I did here. It took a while to shoot this pistol, as I had to wait to get the silencer cleared. Since they sent the gun and can as a set, it was only right to review them as such. GA’s Hub/Dual Lock mounting system makes it easy to swap cans among other GA-mount-equipped rifles, but I imagine the suppressor that came with the gun will stay with it. 

Black Hills supplies my review ammo, for which I am grateful, so I grabbed an assortment and headed to my new, other-side-of-the-ditch 50-yard range and did some shootin’. Here’s what happened…

I grabbed a 50-round box of BH 62 -grain Dual Performance loads and a handload that consisted of a Hornady 55-grain JSP bullet over 24.5 grains of W860 powder… this is one of several loads I have sitting around that was handy, so I grabbed it.

I went through the box and several handloads. Here are a couple of representative targets…

The velocities are evident. These are not exactly earth-shaking, but I am not the best shot in the room. Plus, if I had mounted a scope, the holes would have been closer together… At any rate, with load development, this AR pistol will certainly earn its place in my collection. 

Conclusion

I truly like this AR pistol. With its 12.5” barrel, you don’t lose a lot of “oomph” in the ballistics department, and it is truly handy to use. The light suppressor doesn’t make the gun muzzle-heavy like some integrally suppressed ARs I’ve tried, but the gun balances very nicely in your hand just in front of the mag well. You have iron sights that co-witness with the prism scope, and a very nice trigger. Something you might not notice (until it becomes an issue) is the anti-rotation tabbed rail that locks into the upper. The rail can’t move unless you want it to. 

Here it is on my review sample, and another shot from the GA website…

Image: griffinarmament.com

All in all, this GA Mk 2 is a solid performer with great build quality, top-notch hardware, and a lifetime warranty. It will do everything I need a 5.56mm pistol to do… I think that, in time, it will become my first-grabbed AR in the event of an “event” in my yard. It’s lighter than most, very handy, and it just plain works. Add in the Viridian 4K Duo light/laser, the prism sight, and the suppressor, and what more needs to be said?

Links To Items Used In This Review 

Athlon Rangecraft Velocity Pro Radar Chronograph, $500

Birchwood Casey Filled Shooting Bags, $40

Birchwood Casey Stick-A-Bull 12 Inch Adhesive Bullseye Target, $9

Birchwood Casey Range Cleaning Kit, $60

Black Hills Ammunition

Caldwell E-Max Low-Profile Hearing Protectors, $33

Caldwell 66% AR500 Steel Silhouette Target, $127

Caldwell Ultimate Target Stand, $33

Clear Ballistics Gel, various prices

GPS Medium Range Bag, $150 

MTM Case-Gard High-Low Shooting Table, $160

Wheeler Trigger Pull Gauge, $88