Use of a quality lower that’s been registered as an SBR is a must when dealing with this 12-inch upper from AR57. Author’s Spike’s Tactical lower is still going strong with thousands of rounds through it.

Walking past the AR57 booth, their line of wares caught our eyes.

I had previously seen the AR57 16- inch uppers, but I disdain long barrels on tactical rifles—to me anything longer than 12 inches is pushing it. So when I noticed that AR57 offered barrels in 11, 12, and 16 inches and even an ultra-short six-inch version for the 5.7 Gemtech suppressor, I put my mental truck in park and got out for a 5.7mm lesson.

The 5.7x28mm round has an interesting pedigree. The 5.7 was designed with the specialty soldier in mind. No, I don’t mean spec ops, but folks like the crews of fighting vehicles, heavy weapons operators, and drivers. The idea was to give soldiers in support roles more firepower than a 9mm could deliver but have it packaged in a tiny rifle. This rifle needed to be considerably smaller than an M16 but able to stop armored threats out to 200 meters. Out of this effort was born the P90.

Jump ahead about 15 years and look at what the P90 is now being tasked with. If you happen to catch a glimpse of Secret Service agents in the treeline while the President is making his way to Marine One, you’ll see P90s on slings. If the Secret Service, the world’s foremost dignitary protection agency, is using a particular round and weapon system, you can rest assured that they gave it more than a cursory look before adopting it.

AR57 in SBR configuration is well suited for vehicle operations.
With 5.7x28mm round, threat suppression is possible even through windshields.


“I want one!” was the first thing I said when I saw a P90 put through a 50-round mag dump several years ago. I watched closely as the operator “Groucho walked” at the rubber target dummy. When his P90 ran empty, he moved to cover and threw in another 50 rounder. I was hooked—right up until I saw the P90’s price tag. Say what—$2,800? You must be out of your mind if you think I’m gonna pay that. I don’t pay full price for nothin’ except a Harley-Davidson!

I sadly put aside my dream of owning a P90 until I saw the AR57 at SHOT. A complete upper for $695 is more in my price range. If you’re lucky enough to have an SBR or a Class III departmentissued AR, you’re done. All you have to do is slap one of these uppers on and go at it. If you don’t have a registered AR lower yet, do so—it’s the best $200 you’ll ever spend.

If you’re concerned that 5.7 might be expensive to shoot, think again. It’s priced comparatively to 5.56mm.

The first trigger pull was very surprising. I was expecting some sort of “oomph” from the gun, but instead got this very smooth push straight back into my shoulder. The optic never even left the kill zone on the target. This is because the AR57 uses a very heavy buffer (8.11 oz.) to retard the bolt’s rearward travel long enough for chamber pressure to drop. The heavy buffer and the tolerances engineered into the robust monolithic upper make felt recoil almost nil.

As on the P90, the low-profile 50- round magazine sits above the barrel. This helps the weapon feel balanced even when fighting from the ground with it. Spent cases are ejected straight down through the mag well and make a neat little pile at your feet. If you’re conducting dynamic shooting drills, the guys around you will love you because you won’t be slinging hot brass down their shirts—been there too many times.

The simple blowback operation with a free-sliding bolt means that there’s no gas system to foul with carbon. The monolithic receiver is machined from a single block of aluminum, with four long rails of Picatinny space for mounting accessories.

The 4140 chrome alloy, GBQ Parkerized barrel is free float mounted, thread locked with red Loctite, and torqued to specs. The flash suppressor is threaded 1/5X28 to match all barrel devices and suppressors currently on the market, and the barrel twist at 1:8.5 produces very tight patterns.

Side-mounted charging handle is perfectly placed for quick chambering or clearing rounds.
If you need to contend with a malfunction (such as this simulated partial extraction), removing magazine opens entire top of upper for easy access.
Groove just under front sight needs to be aligned with magazine slot to properly seat the mag. This proved to be a little tricky when under stress.
With a full set of rails on three sides, monolithic AR57 upper is ready for accessories galore.
AR57 standard flash hider is efficient at its duties and adds great aesthetic appeal to the upper.
Rotary function of AR57 mags rotates each round 90 degrees to align it with chamber.


The right-side charging handle is out of the way and yet easily accessible when you need it. My only gripe about it is that I couldn’t lock the bolt to the rear. This is one of those American things that we like our guns to do for us, but it’s impossible due to the design of the P90 mags being employed with the AR57. There’s no conventional follower involved in this magazine. The special rotary follower, which turns the round about 90 degrees, makes it possible to have such a high-round-count mag neatly tucked atop the compact upper, but doesn’t allow for a bolt catch design.

After a bit of thought, I realized that my attitude was born out of my affinity for ARs, but a bolt catch is a feature that isn’t needed with the AR57. There’s nothing for you to do inside the chamber of this weapon. If you have a malfunction, just do a tap-rack-bang drill and move on. If it still doesn’t go bang, launch the mag by pulling the ambi mag release to the rear and tilt the gun in any direction. The open-top design will send the mag flying, you now have a completely opentop gun, and there is absolutely nothing between you and the chamber. Clear whatever the hang-up is, slap another 50 rounder on top, and you’re back in the fight.

My final issue is with the lack of magazine guides to aid with fast reloads. This really is a bit of an issue because there’s only one way this mag will seat properly. It has to match up to the front of the upper, where a protrusion seats into the groove molded into the front of the mag.

Magazine seating is aided on the P90 by the presence of the Collimator sight that sits atop the weapon. The mag actually goes down into the weapon and then you smack it with the heel of your hand and cycle the bolt. With the AR57, it requires a concerted effort to get the mag seated properly because it tends to wobble back and forth across the open top of the rail design. Even a small set of guide rails on either side would help to make mag changes easier.

What used to be a mag well becomes a gigantic ejection port for the AR57. Author likes this design for its unique use of well-established AR-15 platform.
5.7x28mm round (center) compared to .45 AC P and 5.56x45mm. Though the 5.7mm will never be a .45 or a 5.56mm, it’s certainly efficient at doing its intended job of being a CQC killer inside of 200 meters.
Shooting was blazing fast due to lack of recoil from the smooth cycling upper.


Because I’ve been shooting ARs for so many years, my internal “reload meter” begins to sound off by round 15 or 20. With the AR57, reloads could potentially be removed from an engagement due to the fact that after expending 20 rounds, you still haven’t reached the halfway mark on your 50- round mag. That’s a big plus when things get “ugly and fast” … and when was the last time a firefight was “slow and pretty”?

While we’re on the subject of mags, it bears noting that you need to stick with quality FN mags for use with the AR57. Aftermarket mags have been found to cause malfunctions, and in a weapon system this simple it’s very easy to narrow down the cause of malfunctions. Mags are priced at about $30, so don’t feel you need to sell a kidney to make sure you have a stack of mags to work with.

5.56MM VS. 5.7MM

You may be wondering how the 5.7mm fares against the 5.56mm. The simple answer is that the 5.56mm is better at stopping the enemy. That statement, however, has to be qualified with the phrase “for its intended use.”

The P90, and subsequently the AR57, weren’t meant for engagements out to 500 meters. They were meant for engagements inside 200 meters. Inside that range, the 5.7mm hits fairly hard. Here’s some data for the two rounds that are most commonly used.

If you’re law enforcement or military, try to use the SB193 55-gr. rounds. At 1,000 feet-per-second (fps), the effective range is 100 meters. Private citizens or sport shooters should use the SS197SR 40-gr. V-Max, which has an effective range of 150 meters at 2,100 fps. The SS197SR rounds crank out 340 foot-pounds of energy as opposed to 120 foot-pounds from the SB193. While the SS197SR is not armor piercing like the SB193, it does hit sufficiently hard on home invaders and will make them wish they hadn’t entered your home. Not to mention that with the almost non-existent recoil on the AR57, there’s no reason you can’t 50-round mag dump their butts down the stairwell, body armor or not.


For the range, I set up the AR57 with a simple but very rugged optic called the MRDS by Insight Tech Gear. The MRDS is the recent winner of the DoD’s Miniature Reflex Sight trials and has become one of my favorites for CQC guns like this one. With a self-adjusting 3.5 MOA red dot, target acquisition is super fast. The optic proved to be a good choice on the range and helped me stay on target while shooting on the move and around my vehicle.

As noted, the recoil on the AR57 is so slight that it begs you to shoot it more than just a double tap or two. While I enjoy mowing stuff down at high speed inside the 15-yard line, I really was curious how this weapon would do at speed drills from 25 yards. The groups that I got at four inches from standing unsupported were impressive, and that’s four inches at just below full-throttle run-ngun mode.

The entire time I had this upper, I marveled at how smoothly it cycled and how absolutely devoid of malfunctions it was. By the end of this weapon test, my views about the 5.7mm round had completely changed. Even when I conducted windshield tests, the AR57 had more than enough power to blow chunks out of an anti-spall windshield and keep going downrange. The 5.7mm truly deserves a second look by agency heads who refuse to use 5.56mm ARs.


If you find yourself in a position to try one of these AR57 uppers, do it. They’re comparably priced to a quality AR upper. The complete 16-inch weapon sells for $1,099.00.

With the solid monolithic construction of the upper and the interchangeable top rail panels, there are many combinations that can be achieved to find the perfect set-up for your tastes. AR57’s very informative homepage is www.57center. com. There you’ll find a wealth of details to help you make an informed purchase and get the most out of your AR57 experience.

Companies that put an equal amount of effort into their website and customer service usually have a quality product on the market as well. Both ring true in this instance.

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