The AR-57 Could Be the Weirdest AR Variant You’ll Ever See

What happens when you cross an AR-15 with an FN P90? You get arguably one of the weirdest variations to have ever come out of the ages-old AR platform — the AR-57.

Chambered for 5.7×28 mm

Originally, the 5.7×28 mm round that the AR-57’s name refers to was developed in the 1990s as part of a NATO plan to replace 9×19 mm as the new standard sidearm round with all NATO members.

The plan revolved around the primary requirement to build a cartridge that could be used with personal defense weapons as well as pistols. It had to demonstrate better performance metrics and terminal ballistics than 9mm, and needed to be armor-piercing.

FN Herstal came up with the 5.7×28 mm round as a result, paired with its P90 PDW and later the Five-seveN pistol. NATO’s plan went absolutely nowhere, and FN was forced to look elsewhere (including the commercial market) to find buyers for its futuristic cartridges and guns.

For years, FN’s Five-seveN and its semiautomatic PS90 dominated the 5.7 mm gun arena, but in 2008, the AR-57 popped out of nowhere, an alternative to the PS90 albeit with the AR layout so many gun owners find familiar.

However, while the AR-57 bears a resemblance in passing, it’s anything but an AR-15.

Unusual Features

For starters, it uses PS90 top-loaded 50-round mags, which hold rounds perpendicular to the barrel, swiveling them into the forward-facing position to line up with the chamber.

AR-57 P90/PS90 magazine top loaded 50-round magazine.
A P90/PS90 mag showing the unique perpendicular feed (Photo Wikimedia Commons by ROG5728)

The AR-57 sacrifices some of that AR customizability we’ve all come to know and love by making use of a monolithic upper receiver system with the barrel threaded directly into the upper. Instead of a gas-tube operating system, the gun uses straight blowback to cycle rounds and ejects spent casings through the magazine well of the lower.

Early versions of the AR-57 featured a non-reciprocating charging handle on the right side of the upper and a 3, 6, and 9 o’clock Pic rail on the handguard, with a small 12 o’clock rail for a front sight. Eventually, an upper with an MLOK handguard and an ambidextrous charging handle came to fruition as an alternative.

AR57 LLC, the company that produced the weapon, offered buyers a pair of options — a complete upper that could be mated to any AR-15 lower and work with most mil-spec fire control groups, or a complete gun.

So What Exactly Was the Point of the AR-57?

It’s hard to say.

The AR-57 was loosely marketed as a PDW, retailing with 12- and 16-inch barrel options. With absurdly light recoil and a high-velocity round, the AR-57 was guaranteed to pack a decent punch at closer ranges.

By 2017, the AR-57 began its fade into the ether, and today, not much exists to suggest that it was ever commercially successful, though complete guns, as well as the monolithic uppers, still pop up from time to time. Atlantic Firearms also sells complete guns, with the caveat that the sales will continue until supplies run out.

It stands to reason that the top-loaded magazine would’ve also been a factor in the gun’s popularity demise. Perhaps the biggest nail in the coffin was that the AR-57 was too early for the market, hitting shelves at a time when 5.7 mm rounds were just too niche to most consumers.

The CMMG Banshee 100 Mk4 is one of a few PDW options in 5.7 mm available today.
The CMMG Banshee 100 Mk4 is one of a few PDW options in 5.7 mm available today (Photo CMMG)

Today with the advent of the Ruger-57, and CMMG releasing a variety of PDW options chambered for that caliber, 5.7 mm is slowly clawing its way out of obscurity. Maybe the AR-57, if released today, would find a much more receptive and tolerant audience, but alas, it just wasn’t meant to be.

Oddly enough, the AR-57 has somehow made its way to Venezuela, where it was photographed during last year’s attempted coup.

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Ian D'Costa

Ian D’Costa is a contributor with Breach Bang Clear whose work has been featured with Military Times Gear Scout, We Are The Mighty, The Aviationist, and Business Insider. An avid outdoorsman, Ian is also a guns and gear enthusiast.

Ian D'Costa has 3 posts and counting. See all posts by Ian D'Costa

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