CMMG 4.5" .22LR Medium Contour AR-15 Barrel and Collar

Manufactured by CMMG
SKU: 22D5BC4
MPN: 22D5BC3
Manufactured by CMMG
3 Reviews
$129.95 $149.95

In Stock

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Are you tired of spending large amounts of money on 5.56 ammo just to have fun at the range? This 4140 Chrome Moly Steel barrel fits into Mil-Spec AR-15 upper receivers so you can shoot all day with little expense. All that is needed to finish the conversion is this barrel, a CMMG 22lr Arc bolt group, and a CMMG 22Arc magazine. This barrel also comes with a collar that lets you replace the chamber adapter that comes on the 22lr Arc bolt group. The sporting chamber offers more reliable function than the standard chamber. It is fully nitride inside and out to give it high corrosion resistance and longevity. This conversion gives you the benefit of the modularity of the AR-15 platform and ergonomics while saving money on ammo. The extremely short barrel length also makes a great compact carbine or pistol that can be easily stored away or hidden. It is also a great option for training people to use the AR-15 weapon system before moving them to the larger .223 cartridge.

Note: NFA laws apply to this product. It must be attached to a pistol or a legally registered SBR.

  • Easily convert your AR-15 to 22lr to save money on ammo
  • Attaches like a standard AR-15 barrel
  • Great for training people on how the AR-15 weapon system functions
  • Made from high quality 4140 Chrome Moly Steel
  • Salt bath nitride finish
  • Threaded 1/2x28 so you can attach standard .223/5.56 muzzle devices

A leading manufacturer of AR-15 rifles, kits, and accessories, CMMG Inc. was established in 2002. Constantly pushing the edge, CMMG strives to develop and improve bringing you a product lineup that is second to none.
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Barrel CoatingSalt Bath Nitride
Barrel ContourMedium Taper
Barrel Length4.5
Barrel LiningSalt Bath Nitride
Barrel Material4140 Chrome Moly Steel
Caliber Gauge.22 LR
Feed RampsSingle
Gas Seat DiameterN/A
Gas System LengthBlowback
Thread Pattern1/2 X 28
Twist Rate1:16

WARNING: This Product can expose you to chemicals which is known to state of California to cause Cancer and Reproductive Harm. For more information, see

Ratings & Reviews

3 reviews

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Great fun!

by -

Bought this for an AR-22 build. Also bought a CMMG conversion kit. Good way to get a bolt and magazine for the build. Bolts were difficult to find in stock. Finished built shoots fantastic.

Fantastic, Fun, & Accurate for Length of Barrel


This 4.5 in barrel with dedicated collar is awesome! I am able to constantly hit my 3" gongs at 50 yards and my 10" gong at 100 yards with decent grouping in the paint. The optic used on the upper is a Sightmark Ultra Shot Z Reflex. This is one of my favorite uppers and I take it to my range all the time.

Keeping everything subsonic!


This little barrel is a must if you want to build a dedicated AR pistol in 22lr for use with a suppressor. Mini-mags will come out at subsonic speeds. The only round I have found that goes super is the Stinger. Plenty accurate and with the CMMG BCG the gun will run like a sewing machine. All you need is a upper, barrel nut and your favorite hand guard. If you own a 22 suppressor this little barrel allows means you no longer need to buy subsonic 22 ammo. Just tons of fun.