Just built a 12" Grendel using an Odin Works barrel and bolt carrier. 123 grain Hornady Amax through the Recce 7 sounds great, low tone and just under the report of a 22 mag rifle maybe.
Very excited about this combo. Odin barrel is nice quality, about a. 074" gas port. Comes with adjustable gas block. Puts the empties about 5 feet away, locks open every time. I would recommend springing the extra to upgrade to the click-adjustable clamp on gas block especially if you are running a long handguard. Also the barrel is not dimpled, but they were nice enough to put line up marks on the barrel and the block.
I'll still keep my Blackout upper for subs but honestly this setup takes a lot of the shine off the BLK!