Great adjustable gas block - Seekins Precision Low Profile Adjustable Gas Block

I've used these on three builds and they have always worked great for me. I would suggest getting the rifle tuned prior to putting a handguard on as sometimes the set screw doesn't line up properly with different brands handguard holes. Much like any other adjustable gas block they become fairly non-adjustable after they get caked with carbine. Point of this is being able to tune the rifle when you build it not necessarily adjust it for the life of the rifle.