Blending into an urban environment isn’t all that hard—until you need to bring a carbine or precision rifle along, too. Even these days, with all the movies, video games and media coverage, a person carrying a rifle draws a lot of attention, even if you use a hard case or some camouflaged or drab-colored bag. But I’ve come up with a better solution that allows you to carry a compact carbine and a more precision-oriented rifle at the same time in one simple, discreet bag.

I jokingly refer to this concept as “the primitive switch-barrel.” Switch-barrel rifles have been very popular lately. They allow you to use different barrel lengths and calibers as needed. But you’ll also need a different sighting system every time you transition from close- to long-range engagements, and removing/reinstalling optics makes it very easy for them to lose their zero. Thankfully, with the AR platform you can just switch out your upper receivers. Leave the optic on the long-barreled upper and keep a red dot on the shorter upper. Switching uppers takes less time than switching barrels, and it ensures you’ll still be on target afterward.

You can do this with a number of AR-platform rifles, but so far Primary Weapons Systems (PWS) has offered the best options for my “two guns, one bag” concept.

PWS Combo

One of the most reliable short-barreled ARs I’ve ever tested is the PWS MK107. It typically runs a wide variety of ammunition and will also work reliably with a sound suppressor—not something every 7- to 8-inch-barreled AR can do. Of course, PWS recently unveiled its MOD 2 design upgrade, and this seemed like a great opportunity to try it out.

The MK107 MOD 2 is a piston-driven AR with a short 7.75-inch barrel. The gas piston operating system can be adjusted to three different positions to compensate for sound suppressors, various ammunition, heavy fouling, environmental conditions, etc. The chrome-moly barrel has a QPQ coating for corrosion resistance, and it comes fitted with PWS’ CQB compensator, which helps mitigate muzzle blast in close quarters.

Surrounding the barrel and piston system is a new handguard with PicMod technology. KeyMod slots run the entire lengths of the sides and bottom, but Picatinny slots are machined near the front so you can quickly add whatever accessories you might need. You won’t have to worry about rails coming loose.

Upper & Lower

Strong yet lightweight, the MOD 2 upper and lower receivers are forged from 7075-T6 aluminum. The upper features a hardened bolt carrier group made from tool steel. The lower comes with ambidextrous controls, including the safety selector, magazine release and bolt release. The enhanced trigger is factory set for a crisp 5.5-pound pull.

The lower also features a redesigned buffer tube made from extruded 7075-T6 aluminum with PWS’ new Rachet-Lock design, which eliminates the need for a staked castle nut. The buffer tube is fitted with a collapsible polymer BCM Gunfighter stock that complements the BCM Gunfighter pistol grip.

For long-range engagements, I also tested an MK116 MOD 2 upper with a 16.1-inch barrel and a correspondingly longer PicMod handguard. This upper is similar to the MK107’s, with lightening cuts along the sides of the receiver. Three synthetic rail covers were included with the upper to provide a solid support-hand grip, and the barrel came capped with PWS’ FSC (Flash Suppressing Compensation) muzzle device.

Optics & Accessories

For short-barreled rifles (SBRs), I prefer to use a red-dot sight along with fixed front and rear backup sights and a flashlight mounted at 12 o’clock. The Trijicon SRS remains one of my favorites for this setup because it provides a wide field of view with no tunneling effect. Fixed sights are necessary because you might not have time to flip up sights if your red dot is occluded or inoperable. That’s why I turn to Daniel Defense’s fixed rail-mounted sights, which only show in the lower third of the Trijicon SRS’ sight picture. For the flashlight I chose my trusted SureFire X200. My final additions included a BCM KeyMod foregrip and a Law Tactical Gen3
Folding Stock Adaptor.

Thanks to some top-notch training with Follow Through Consulting, I’ve become hooked on scopes with TReMoR 3 (T3) reticles for fast targeting out to 500 meters. So I added a Leupold 3-18x44mm Mark 6 scope with an illuminated T3 reticle to the MK116 MOD 2 upper’s top rail along with Griffin Armaments’ Fail Safe Angle sights.

Now to hold it all together. With the MK107 MOD 2’s stock folded, it’ll fit in a bag that’s only 18 inches long, like a standard hydration pack. Of course the goal here is to carry the SBR and upper together. This requires a larger bag like the Elite Survival Systems Stealth. Designed for law enforcement use as a covert pack, the Stealth accommodated the folded MK107 and MK116 upper with all of their accessories, including a bipod. It also held spare magazines, a first-aid kit, a sling, water and snacks—pretty much all you would need for a deployment or bug-out situation lasting a few hours.

Zeroing In

As mentioned, the goal of this system is to provide two rifle setups without having to switch sights around and lose your zero. Field testing proved this concept; removing and reinstalling the upper receivers did not cause their sights/optics to shift or lose their zero. I zeroed both uppers with Black Hills’ 69-grain Tipped MatchKing (TMK) ammunition. It’s designed to expand at velocities slower than 2,000 fps, making it perfect for short barrels. This allowed me to use one round for both uppers.

While switching back and forth over 10 separate cold-bore shots, there was little if any shift in the point of impact. At 100 yards, the MK116 MOD 2 put everything inside an inch. Using my truck as an impromptu rest, 10-shot groups with the Black Hills 69-grain TMKs were all smaller than 2 inches. In short, after seeing just how accurate and reliable this setup was, I would not hesitate a second to deploy with it.

The MK107 MOD 2 performed similarly at 50 yards. Using my truck bumper as a rest, my groups all measured less than an inch at 50 yards. At 25 yards, it created one big hole. Again, switching the uppers did not cause a shift in the point of impact. I was very pleased with the Trijicon and Leupold optics used for both rifles.

After Action Report

The MK116 MOD 2’s FSC muzzle device did a pretty good job of keeping me on target with less muzzle blast coming back my way. I also tested this rifle with SureFire’s WarComp 556 flash suppressor/adapter and the SOCOM556-RC2 sound suppressor. The WarComp performed like the FSC—it wasn’t much louder, and the blast was similar. The MK116 ran well with the SOCOM556-RC2 with no change in accuracy and only a vertical point-of-impact shift of about an inch.

PWS’ CQB is an excellent brake for sending muzzle blast forward. Firing at a moderate pace, you’ll barely notice any flash with most ammunition. Rapid-fire strings result in a small fireball every few rounds. But it made the MK107 MOD 2 very pleasant to be behind or beside when firing.

The enhanced two-stage trigger was crisp with no creep or overtravel, and the reset was both audible and tactile. At 5.5 pounds, it’s just about right for most duty applications. It’ll meet the minimum for many law enforcement agencies. Also, I found the ambidextrous controls worked well and were positioned properly. The controls were intuitive and easy to activate.

Final Shots

I had been looking forward to testing PWS’ new MOD 2 rifles since the 2016 SHOT Show. They certainly did not disappoint here. Both of the uppers were accurate and reliable, with the soft shooting impulse that long-stroke gas piston systems offer. Their fit and finish were excellent, with tighter lines and better ergonomics than their predecessors. These uppers were also lighter, stronger and sleeker. The PicMod system is extremely practical and efficient, too, keeping both of these handguards slim and lightweight.

Ever since my first range trip, I’ve kept the PWS MK107 and MK116 handy inside the Elite Survival Systems Stealth. This setup is very slick. You really can’t beat this kind of convenience—just grab the bag and everything is ready to go. My preference these days is to leave the MK107 intact given where I live, but you can pack it either way. It’s a tighter fit with the lower on the MK116, but it works. If you’re considering replicating this setup, you’ll probably need to start with the MK107 because it has to be registered with the BAFTE, then add the MK116 upper. All in all, this is a very handy setup that will help you tackle threats up close and 800 yards away.

PWS MK107 Mod 2 Specs

Caliber: .223 Wylde
Barrel: 7.75 inches
OA Length: 24.6 inches
Weight: 5.55 pounds (empty)
Stock: BCM Gunfighter
Sights: None
Action: Piston-operated semi-auto
Finish: Matte black
Capacity: 30+1
MSRP: $2,050

PWS MK107 Mod 2 Performance

Load Velocity Accuracy
Barnes 70 TSX 2,250 0.65
Black Hills 69 TMK 2,325 0.55
Gorilla 69 SMK 2,140 0.60
Hornady 75 BTHP 2,200 0.75

*Bullet weight measured in grains, velocity in fps by chronograph and accuracy in inches for best five-shot groups at 50 yards.

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This article was originally published in “Black Guns” 2017. To order a copy, visit

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