Upper Parts

AR-45 .45 ACP 4.5" Barrel | 1:16 Twist | 4150 Nitride | 5/8x24 | Moriarti Armaments

Complete your next AR-45 or Micro ARP build with the Moriarti 4.5" .45 ACP Barrel. Precision machined from 4150 Chrome Moly steel and finished in black nitride for enhanced durability and corrosion resistance, this barrel delivers the reliability and accuracy expected from premium American-made components.

Featuring a 1:16 twist rate and 5/8x24 muzzle threads, this barrel is ideal for compact AR-45 pistols, ARP pistol builds, and custom .45 ACP AR platforms. Its 4.5-inch length makes it an excellent choice for builders looking to create a lightweight, maneuverable mini ARP without sacrificing quality or performance.

Whether you're assembling a Micro ARP, upgrading an existing AR-45, or starting a custom build, this barrel provides the solid foundation needed for dependable operation.

Specifications

• Caliber: .45 ACP
• Platform: AR-45
• Barrel Length: 4.5"
• Material: 4150 Chrome Moly Steel
• Finish: Black Nitride
• Twist Rate: 1:16
• Thread Pitch: 5/8x24 TPI
• Application: AR-45 / Micro ARP Builds
• Made in USA

Shop Related Categories

• AR-45 Complete Uppers
• AR-45 Bolt Carrier Groups
• AR-45 Lower Receivers

What twist rate is best for a .45 ACP AR barrel?

A 1:16 twist rate is the industry standard for most .45 ACP AR barrels, providing reliable stabilization for common factory ammunition across a wide range of bullet weights. It offers dependable performance for recreational shooting, training, and custom AR-45 builds.