CMMG Radial Delayed 9MM Barrel and BCG Assembly 5"

SKU: 99D17C3
MPN: 99D17C3
Manufactured by CMMG


Out of Stock

NOTE: Limit 2 per household. Quantities exceeding 2 will not allow checkout.


Out of Stock


The National Firearms Act regulates the configurations of some firearms assembled with barrels under 16” long. Know the NFA laws in your state before purchasing this item.

Excited to build a pistol caliber carbine but don’t want to deal with spending time and money trying to find the correct buffer weight to reliably cycle the blowback action and then still have to deal with harsh recoil? Now you can forget about all that headache with the CMMG Radial Delayed Barrel and BCG assembly chambered for 9mm Luger. This kit utilizes the same radial delayed blowback system from the Guard series of PCC’s but allows you to build yours from the ground up, so you can build it to your preferences with ease. This system uses a bolt like an AR-15 without the gas system and with specific cuts on the lugs that force the bolt to rotate and delay the action from cycling in order to reduce felt recoil and increase reliability. This also has the benefit of being able to use a lighter BCG, so there is not a huge mass of steel slamming back and forth in your receiver. The gas key is still present for the sole purpose of interacting with the charging handle. Build your dream 9mm carbine with CMMG.

  • 5” barrel chambered in 9mm
  • Medium taper profile with 1:10 twist rate
  • Threaded 1/2x28
  • 4140 Chrome Moly steel with Nitride finish
  • Radial delayed blowback bolt
  • Requires enlarged ejection port for proper function
  • Lighter than standard blowback bolts

The 5” barrel in this kit is machined from 4140 Chrome Moly steel with a salt bath Nitride finish and threaded 1/2x28 for muzzle devices. This kit is also designed to function with the CMMG Guard 9mm receivers with enlarged ejection ports and may not work with other brands.

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.


Barrel CoatingSalt Bath Nitride
Barrel ContourMedium Taper
Barrel Length5.0
Barrel LiningSalt Bath Nitride
Barrel Material4140 Chrome Moly Steel
Caliber Gauge9mm Luger
Feed RampsMonolithic
Gas System LengthBlowback
Thread Pattern1/2 X 28
Twist Rate1:10

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

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