Cmmg 4.5 Barrel Sub-Assembly W/ Collar Kit 22Lr

The CMMG 4.5" Barrel Sub-Assembly with Collar Kit is built for shooters who want a dedicated .22 LR upper receiver for their AR-15 platform. This compact barrel configuration lets you add a specialized .22 training or practice upper to your existing AR lower receiver, giving you a versatile rimfire option without committing to a full rifle build. The included collar kit handles the interface between your conversion setup and the barrel, making installation straightforward.

Durability is built in: CMMG machines these barrels from 4140 chrome moly steel and applies a salt bath nitride finish inside and out, so you're getting the same heat treatment and corrosion resistance you'd expect in a centerfire barrel. The 1:16 twist rate stabilizes standard .22 LR ammunition reliably, and the sporting chamber is the industry standard for .22 AR conversions. Threading is 1/2-28", which accommodates common rimfire suppressors and muzzle devices if you go that route.

This is the short 4.5" version—ideal if you're building a truck gun, integrally-suppressed rig, or just prefer a handy overall length. Pair it with an upper receiver kit and your favorite .22 LR lower, and you've got a quieter, lower-recoil trainer that shares controls and ergonomics with your centerfire platform.

Key Features

• 4.5" barrel length for compact, maneuverable profile
• 4140 chrome moly construction with salt bath nitride finish for corrosion and wear resistance
• 1:16 twist rate optimized for standard .22 LR ammunition
• .22 LR sporting chamber for reliable cycling
• 1/2-28" threading for suppressors and accessories
• Collar kit included for easy barrel-to-upper interface
• Drop-in compatibility with AR-15 upper receiver builds

Specifications

Frequently Asked Questions

Will this barrel work with my AR-15 lower receiver?

Yes. This is a .22 LR upper assembly barrel designed to pair with a .22 AR conversion kit or dedicated .22 upper receiver on a standard AR-15 lower. You'll need a .22 LR bolt carrier group and magazine to complete the upper.

What's the barrel collar kit for?

The collar kit replaces the chamber adapter on .22 AR conversions, providing the proper interface between the barrel and your conversion or upper receiver assembly. It's included with this sub-assembly to simplify your build.

Can I suppress this barrel?

The 1/2-28" threading is standard for rimfire suppressors. Many shooters pair .22 LR uppers like this one with a can for quiet, pleasant plinking—though you'll need to verify any suppressor is rated for rimfire use and check local regulations.

What ammunition does the 1:16 twist stabilize?

The 1:16 twist is optimized for standard .22 LR ammunition. This is the most common twist rate for .22 LR barrels and will cycle and stabilize typical rimfire rounds reliably.