$336.61
Availability: In Stock
The CMMG 22LR 4.5" 4140CM Replacement Barrel & Bolt Group Kit is a straightforward way to convert your AR-15 into a dedicated .22 LR rimfire trainer. Instead of buying a second rifle, this conversion kit lets you keep your existing lower receiver and swap in CMMG's complete upper assembly—barrel and bolt group together—to shoot affordable rimfire ammo downrange. It's popular with shooters who want to run drills, zero fundamentals, or just practice trigger control without the cost and report of centerfire rounds.
The barrel is a 4.5-inch 4140 chrome-moly steel tube with a salt-bath nitride finish for durability and corrosion resistance. CMMG optimized the 1:16-inch twist for the wide range of commercial .22 LR ammunition, though the system performs best with 36-grain round-nose bullets. The muzzle is threaded at 1/2-28 TPI, so you can attach a suppressor or adapter if your setup allows. A .22 LR sporting chamber rounds out the barrel, giving you reliable, safe function in rimfire.
The bolt group is matched to the barrel and designed to run in your AR-15 lower. One important note: CMMG recommends using a round-style hammer instead of the notched hammer in your centerfire lower to avoid function issues with the rimfire bolt. You'll also need a dedicated .22 LR magazine to complete the conversion—the kit itself supplies the barrel and bolt assembly only.
| Caliber | .22 LR |
| Barrel Length | 4.5 inches |
| Barrel Material | 4140 Chrome-Moly Steel |
| Barrel Finish | Salt-Bath Nitride |
| Barrel Twist | 1:16 inch |
| Muzzle Thread Pitch | 1/2-28 TPI |
| Chamber Type | .22 LR Sporting |
| Barrel Profile | Medium Taper |
| Model | 22D5B6E |
Yes, the kit is designed to drop into a standard AR-15 lower. You'll keep your existing lower and fire control group; just swap out the upper assembly. However, CMMG recommends using a round-style hammer instead of a notched hammer to avoid function problems with the rimfire bolt.
The 1:16-inch twist is compatible with most commercial .22 LR ammunition on the market. CMMG notes that the system runs best with 36-grain round-nose bullets for optimal reliability and performance.
The muzzle is threaded at 1/2-28 TPI, so you can attach a compatible suppressor or muzzle device if your local laws and setup allow it.
The kit includes only the barrel and bolt group assembly. You will need a dedicated .22 LR magazine to feed and cycle the rimfire ammunition.
SKU: 121687554 • Width: 1.9in • Height: 1.8in • Depth: 11.7in • Weight: 1.11oz
Availability: In Stock
The CMMG 22LR 4.5" 4140CM Replacement Barrel & Bolt Group Kit is a straightforward way to convert your AR-15 into a dedicated .22 LR rimfire trainer. Instead of buying a second rifle, this conversion kit lets you keep your existing lower receiver and swap in CMMG's complete upper assembly—barrel and bolt group together—to shoot affordable rimfire ammo downrange. It's popular with shooters who want to run drills, zero fundamentals, or just practice trigger control without the cost and report of centerfire rounds.
The barrel is a 4.5-inch 4140 chrome-moly steel tube with a salt-bath nitride finish for durability and corrosion resistance. CMMG optimized the 1:16-inch twist for the wide range of commercial .22 LR ammunition, though the system performs best with 36-grain round-nose bullets. The muzzle is threaded at 1/2-28 TPI, so you can attach a suppressor or adapter if your setup allows. A .22 LR sporting chamber rounds out the barrel, giving you reliable, safe function in rimfire.
The bolt group is matched to the barrel and designed to run in your AR-15 lower. One important note: CMMG recommends using a round-style hammer instead of the notched hammer in your centerfire lower to avoid function issues with the rimfire bolt. You'll also need a dedicated .22 LR magazine to complete the conversion—the kit itself supplies the barrel and bolt assembly only.
| Caliber | .22 LR |
| Barrel Length | 4.5 inches |
| Barrel Material | 4140 Chrome-Moly Steel |
| Barrel Finish | Salt-Bath Nitride |
| Barrel Twist | 1:16 inch |
| Muzzle Thread Pitch | 1/2-28 TPI |
| Chamber Type | .22 LR Sporting |
| Barrel Profile | Medium Taper |
| Model | 22D5B6E |
Yes, the kit is designed to drop into a standard AR-15 lower. You'll keep your existing lower and fire control group; just swap out the upper assembly. However, CMMG recommends using a round-style hammer instead of a notched hammer to avoid function problems with the rimfire bolt.
The 1:16-inch twist is compatible with most commercial .22 LR ammunition on the market. CMMG notes that the system runs best with 36-grain round-nose bullets for optimal reliability and performance.
The muzzle is threaded at 1/2-28 TPI, so you can attach a compatible suppressor or muzzle device if your local laws and setup allow it.
The kit includes only the barrel and bolt group assembly. You will need a dedicated .22 LR magazine to feed and cycle the rimfire ammunition.
SKU: 121687554 • Width: 1.9in • Height: 1.8in • Depth: 11.7in • Weight: 1.11oz