KE Arms KP-15 AR57 5.7x28mm – SIG Sauer ROMEO5 & JULIET3 Micro

Offered for sale is a KE Arms KP-15 semi-automatic rifle chambered in 5.7x28mm, equipped with an AR57 / Five Seven upper receiver, SIG Sauer ROMEO5 red-dot optic, and SIG Sauer JULIET3 Micro magnifier.

This rifle combines two distinctive firearm designs: the KE Arms KP-15 monolithic polymer lower receiver and the AR57 upper receiver system.

The result is an unconventional AR-pattern rifle that utilizes the 5.7x28mm cartridge and a top-mounted magazine arrangement rather than the traditional AR-15 feeding system.

The rifle features black furniture, a fixed stock, integrated pistol grip, ventilated handguard, vertical foregrip, and a muzzle device.

AR57 Upper Receiver – Unique 5.7x28mm Design

The AR57 upper receiver is designed to adapt the AR-15 platform to the 5.7x28mm cartridge.

Unlike conventional AR-15 rifles, the AR57 utilizes a top-mounted magazine system compatible with FN P90-pattern magazines.

This configuration places the magazine horizontally above the upper receiver.

The rifle’s upper receiver is marked:

AR57 – FIVE SEVEN

The caliber marking reads:

CAL. 5.7 x 28 MM

The AR57 design provides an unusual alternative to conventional 5.56 NATO AR-15 rifles and other firearms chambered in 5.7x28mm.

KE Arms KP-15 Monolithic Polymer Lower Receiver

The lower receiver is a KE Arms KP-15, manufactured by KE Arms LLC in Phoenix, Arizona.

The KP-15 differs from conventional AR-15 lower receivers by incorporating the receiver, pistol grip, and fixed buttstock into a single polymer structure.

This integrated design eliminates the need for a separate receiver extension and detachable stock assembly.

The KP-15 was developed as a lightweight alternative to conventional aluminum AR-15 lower receivers.

Its fixed-stock configuration also provides a distinctive appearance compared with traditional adjustable-stock AR-pattern rifles.

The receiver markings identify:

KE ARMS LLC – PHOENIX, AZ – KP-15 CAL-MULTI

SIG Sauer ROMEO5 Red-Dot Optic

This rifle includes a SIG Sauer ROMEO5 red-dot sight mounted on the upper receiver’s Picatinny rail.

The ROMEO5 is a compact electronic optic commonly used on modern sporting rifles.

Its compact construction complements the rifle’s unconventional AR57 configuration.

The optic is clearly identified by its SIG Sauer and ROMEO5 markings.

SIG Sauer JULIET3 Micro Magnifier

Mounted behind the ROMEO5 is a SIG Sauer JULIET3 Micro magnifier.

The JULIET3 Micro provides 3x magnification when positioned behind a compatible red-dot sight.

The combination allows the shooter to use the red dot without magnification or incorporate the magnifier for a magnified sight picture.

The close-up photograph clearly shows the JULIET3 MICRO marking.

The ROMEO5 and JULIET3 Micro are both included with the rifle as pictured.

The operational condition and zero of the optics have not been independently verified.

Modern Handguard and Accessories

This KE Arms KP-15 / AR57 rifle features a ventilated black handguard with elongated accessory mounting slots.

A short vertical foregrip is installed beneath the handguard.

Additional visible features include a full-length optics mounting rail, fixed polymer stock, integrated pistol grip, and ported muzzle device.

The rifle’s configuration combines the AR57’s unusual magazine placement with modern accessory mounting options.

 

KE Arms KP-15 AR57 Specifications

An Uncommon AR-Pattern Rifle

The KE Arms KP-15 / AR57 combination stands apart from conventional AR-15 rifles because of its unusual feeding system, 5.7x28mm chambering, and integrated polymer lower receiver.

The AR57 upper receiver is particularly recognizable because of its top-mounted magazine arrangement.

Combined with the KE Arms KP-15 lower and SIG Sauer optic package, this rifle represents a distinctive example of a specialized AR-platform configuration.

Condition

This is a used KE Arms KP-15 rifle equipped with an AR57 5.7x28mm upper receiver.

Based on the photographs, the rifle features black polymer furniture, a fixed stock, integrated pistol grip, ventilated handguard, vertical foregrip, and mounted SIG Sauer optics.

The rifle displays cosmetic signs of previous handling and use.

A magazine is visible in the top-mounted magazine position. Its capacity has not been verified.

Please examine all photographs carefully for the exact condition, configuration, and included accessories.

The actual firearm pictured is the rifle offered for sale at GunsmithLive.