The CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly does not have a dimpled barrel. This barrel has a 0.750" gas journal and utilizes M4 feed ramps. It is machined from 4140 chrome moly steel with a nitride finish.
I have this barrel and it 100% has a dimple
I received my barrel today after waiting over a month. It IS dimpled (1 cut). .400 center to center. Used my Kaw Valley Precision gas block dimpling jig and cut 2nd dimple into barrel. Love the barrel so far. I'll be finishing the build tomorrow and then straight to range to zero ootic and check accuracy.
On 4/5/2022 I received an email response from CMMG Sales/Customer Service representative that their 12.5" .300 AAC Blackout MR barrel IS dimpled for gas block installation/alignment.