AR-10mm 8.5" Slick Side Pistol Upper with LRBHO, M-LOK Handguard, A2 Flash Hider

AR-10mm 8.5" Upper: Specs

The AR-10MM 8.5" Slick Side Complete Upper is a precision-machined, American-made upper designed for pistol-caliber AR builds. This upper assembly features a slick side billet upper receiver and Last Round Bolt Hold Open (LRBHO) functionality, delivering reliable performance for your 10MM AR platform.

Barrel:

• 8.5" 10MM match-grade barrel

• 4150 Chrome Moly Vanadium (CrMoV) steel construction

• Black nitride finish for corrosion resistance

• Twist Rate: 1:16

• Muzzle Threads: 5/8x24

• Includes A2 Flash Hider

Upper Receiver:

• Slick side non-reciprocating billet upper

• 7075-T6 aircraft-grade aluminum

• Hardcoat anodized black (Mil-Spec Type III, Class 2)

• Compatible with Glock and Colt mag lowers (AR-9/AR-40/AR-45)

• Integrated LRBHO

• Rear dust cover trap door included

Handguard:

• Free-floating, slim 7" M-LOK rail

• Lightweight aircraft aluminum construction

• Black anodized finish

Bolt Carrier Group (BCG):

• AR-40 / 10MM Ramped BCG (Glock & Colt compatible)

• 8620 steel, phosphate coated

• Ramped for use with standard AR-15 hammers

• M-16 cut, full-auto rated (BATFE compliant)

Charging Handle:

• Standard MIL-SPEC AR-15 charging handle included

Gas System:

• Blowback operated – no gas block or gas tube required

Whether you're building a compact 10MM AR pistol or upgrading your setup, this Moriarti Arms upper assembly provides robust features, precision construction, and a smooth shooting experience.

Please Note: Images may not represent the exact product configuration. Rail and small components may vary due to production schedules. Current ETA is 8 weeks.

FAQ

What lower does it fit?

A dedicated pistol-caliber AR lower that takes Glock-style 10mm magazines. A standard AR-15 lower with 5.56 magazines will not feed it.

How does it operate?

It is a direct blowback pistol-caliber design with no gas tube or gas block, so a heavy PCC buffer is used for reliable cycling.

Does it have last round bolt hold open?

Yes. It has LRBHO, so the bolt locks back after the last round when used with an LRBHO-compatible lower.

Is a lower receiver included?

No. This is an upper assembly only; the lower receiver and magazine are sold separately.

Related: AR-10mm upper assemblies · pistol caliber carbines