Micro ARP Pistols & Compact AR Builds

Micro ARP Pistols, Uppers & Kits by Caliber

A Micro ARP is an ultra-compact, semi-automatic AR-15-style pistol with a 3" to 5" barrel — the smallest practical version of the AR platform. Moriarti Armaments, a Miami-based FFL/SOT manufacturer, builds complete Micro ARP pistols and Micro ARP upper assemblies in eight calibers, from 5.56 NATO and 300 Blackout to 7.62x39, 9mm and 10mm.

Shop Micro ARP by Caliber

• Micro ARP 5.56 / .223 – the classic AR-15 chambering in a micro-length package.
• Micro ARP 300 Blackout – a cartridge made for short barrels and a popular suppressor host.
• Micro ARP 7.62x39 – affordable AK ammunition in an AR-style pistol.
• Micro ARP 9mm – compact pistol-caliber (PCC-style) builds.
• Micro ARP 10mm, .40 S&W and .45 ACP – larger pistol calibers.
• Micro ARP AR-10 – compact .308-class builds.

3", 4", 4.5" and 5" Micro ARP Barrel Lengths

Most Micro ARP builds use a 3", 4", 4.5" or 5" barrel. The 3" and 4" models give the smallest overall length; 4.5" and 5" models add a little velocity and handguard space. Each product page lists the exact barrel length, handguard, muzzle device and what is included.

Complete Pistols or Upper Assemblies

Choose a complete Micro ARP pistol, or a complete Micro ARP upper assembly to put on a lower you already own. Many models are available in several colors and caliber options.

Micro ARP FAQ

What barrel lengths do Micro ARPs come in?

Our Micro ARP line includes 3", 4", 4.5" and 5" barrels, depending on the caliber and model.

Can I buy just a Micro ARP upper?

Yes. Our 5.56, 300 Blackout and 7.62x39 Micro ARP uppers fit standard AR-15 lowers. Pistol-caliber (9mm, 10mm, .40, .45) and AR-10 uppers need a matching lower receiver.

How are Micro ARP pistols shipped?

Complete pistols ship to a licensed FFL dealer near you for transfer. Please check your state and local laws before ordering.

Is a Micro ARP a pistol or a rifle?

Micro ARPs are sold as pistols. Adding a shoulder stock to a firearm with a barrel shorter than 16" makes it a short-barreled rifle (SBR), which must be registered under the NFA.

New to Micro ARPs? Read our complete Micro ARP Buyer's Guide →

FAQ

What is a Micro ARP?

A Micro ARP is an ultra-compact AR pistol with a barrel of roughly 3" to 5.5", built on an AR-15, AR-10 or pistol-caliber lower.

Which calibers are available?

5.56 NATO, 300 Blackout, 7.62x39, 9mm, 10mm, .40 S&W, .45 ACP and AR-10 calibers such as .308 Win and 8.6 Blackout.

Do complete Micro ARP pistols ship to an FFL?

Yes. Complete pistols are firearms and ship to your local FFL dealer. Uppers and kits without a lower receiver ship directly where state law allows.

What does "SBR ready" mean?

The rear setup accepts a stock, but adding a shoulder stock to a pistol with a short barrel changes its federal classification. Do it only in compliance with NFA and state rules.

Related: all Micro ARP pistols and uppers · 5.56 Micro ARP · 300 BLK Micro ARP · 9mm Micro ARP