AR-45 .45 ACP 4" Slick Side Complete Upper – LRBHO, BCG & Charging Handle

.45 ACP Micro Upper: Specs & Features

Experience smooth cycling and compact firepower with Moriarti Armaments' AR-45 .45 ACP 4" Slick Side Complete Upper, engineered with an LRBHO (Last Round Bolt Hold Open) billet upper receiver and blowback system. This compact upper is ideal for pistol builds or PDW platforms where space and reliability matter most.

Features

Barrel:

• 4" match-grade barrel chambered in .45 ACP

• 4150 CrMoV steel, black nitride finish

• 1:16 twist rate

• 5/8x24 threads

• Includes A2 flash hider

• Integrated feed ramp for blowback operation

Upper Receiver – LRBHO Slick Side:

• Machined from 6061-T6 billet aluminum

• Non-reciprocating LRBHO mechanism

• Matte black hardcoat anodized (MIL-8625 Type 3 Class 2)

• Compatible with Glock-mag AR-9/.40/.45 components

• No dust cover or forward assist

• Clean billet styling matches AR-9 and AR-45 lowers

• Manufactured to MIL-SPEC on precision CNC equipment

Gas System:

• Blowback operation – no gas tube or port needed

Handguard:

• Lightweight 4" free-floating M-LOK handguard

• Slim profile

• Made from aircraft-grade aluminum

• MIL-8625 Type 3 Class 2 anodized black

Bolt Carrier Group (BCG):

• Ramped AR-45 BCG

• 8620 steel with phosphate finish

• Glock & Colt mag compatible

• M16 cut for legal full-auto compatibility (BATFE regulations apply)

• Ramped to work with standard AR-15 hammers

Charging Handle:

• MIL-SPEC AR-15 charging handle included

This upper assembly is fully assembled and tested for functionality. Weighs approximately 3.2 lbs. Current ETA: 4-6 weeks

Pair it with a Moriarti AR-45 lower receiver to complete your pistol build.

FAQ

Is a lower receiver included?

No. This is an upper assembly only; the lower receiver, magazine and sights are not included.

What lower does it fit?

A dedicated pistol-caliber AR lower, such as a Glock-pattern lower using .45 ACP Glock-style magazines. A standard AR-15 lower with 5.56 magazines will not feed it.

How does it operate?

It is a direct blowback system, so it has no gas tube. 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.

Related: .45 ACP Micro ARP · all Micro ARP pistols and uppers

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