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AR-15 4.5 Barrel & Bolt Group Kit MT 4140CM 22Lr

AR-15 4.5 Barrel & Bolt Group Kit MT 4140CM 22Lr

CMMG · Barrels

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Best price

$289.99at MidwayUSA

In stock checked Oct 1, 2026

Buy at MidwayUSA

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Where to buy

StorePriceAvailabilityBuyAdd to build
MidwayUSA Best price $289.99checked Oct 1, 2026 In stock Buy at MidwayUSA
CMMG $299.95checked Oct 1, 2026 Check store Buy at CMMG
OpticsPlanet $289.49Salechecked Oct 1, 2026 Out of stock Buy at OpticsPlanet
Brownells $312.31checked Oct 1, 2026 Out of stock Buy at Brownells

Prices and availability change often, so confirm on the store's site before you buy. We may earn a commission from these links.

Price history

Lowest in-stock price in the last 30 days: $289.99 at MidwayUSA. Dashed line = out of stock. Tracking since Sep 27, 2026.

Show the prices as a table
StoreLatestLowestHighest
Brownells$312.31$312.31$312.31
CMMG$299.95$299.95$299.95
MidwayUSA$289.99$289.99$289.99
OpticsPlanet$289.49$289.49$294.49

Since Sep 27, 2026.

About this part

The AR-15 4.5 Barrel & Bolt Group Kit MT 4140CM 22Lr is a .22 LR barrel from CMMG. It's sold by 4 stores (1 in stock), from $289.49 to $312.31. The lowest in-stock price in the last 30 days was $289.99 at MidwayUSA.

Fits and works with

Caliber
.22 LR · Shop matching ammo
Bolt
.22 LR · Bolt carrier groups

Specifications

Manufacturer
CMMG
Platform
AR-15

From the manufacturer

An Easy Conversion to .22 LR for Your Upper Receiver

In this Barrel and Bolt Group Kit, CMMG provides everything you need to convert your AR-15 into a dedicated .22 LR rimfire training platform.

The barrel measures 4.5 inches long and is machined from 4140 chrome-moly steel, complete with a salt-bath nitride finish and a medium-taper profile. The barrel is optimized with a 1:16-inch twist that's compatible with most .22 LR bullets on the market, but the system runs best with 36-grain round-nose bullets.

Each .22 LR Barrel and Bolt Group Kit from CMMG also features a .22 LR sporting chamber, as well as a threaded muzzle measuring 1/2-28 TPI thread pitch. CMMG recommends using a round-style hammer in place of a notched hammer to avoid function issues. The only other piece of the kit needed for a functioning system is a dedicated .22 LR magazine.

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$289.99 at MidwayUSA
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