AR-10mm 4″ Side Charging Complete Upper Receiver, LRBHO

AR-10mm 4" Upper: Specs

Engineered for tight quarters and powerful punch, the AR-10MM 4" Side Charging Complete Upper from Moriarti Arms is a top-tier option for compact AR pistol builds in 10mm Auto. Built on a non-reciprocating side charging billet upper receiver, this upper includes Last Round Bolt Hold Open (LRBHO) functionality and comes fully assembled with a ramped BCG and 4" M-LOK handguard.

Whether you're building a compact PDW-style firearm or a backpack gun, this upper is a high-quality, American-made solution compatible with most 45-acp glock style lowers.

Key Features:

• Barrel: 4" 10MM match grade barrel, 4150 CrMo steel, black nitride finish, 1:16 twist, 5/8x24 threads, A2 flash hider

• Upper Receiver: Billet 6061 aluminum, side charging, matte black anodized, LRBHO-ready

• Handguard: 4" free-floating slim M-LOK rail, lightweight aircraft-grade aluminum, hardcoat anodized

• Gas System: Blowback

• Bolt Carrier Group (BCG): Ramped, Glock & Colt mag compatible, 8620 steel, mag phosphate finish

• Charging System: Side charging with adjustable tension slide lock

• Compatibility: Compatible with most AR-15 Glock-mag lowers in 10mm/.40 S&W

• Weight: Approx. 3.2 lbs

• ETA: Ships in 4 weeks

• Country of Origin: USA

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.

What is a non-reciprocating side charger?

The charging handle is on the side of the upper and does not move while firing, so you can charge it without breaking your grip.

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

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