05-09-2021, 10:17 PM
Welcome to the forum! For the Monster barrel, as I recall Krys makes them so the gas block can seat back against the back shoulder of the journal, no feeler gauging required. Double check me on his vendor page he has the details. That can be a concern with various barrels but the ones I really like are set to back up against the shoulder. The gap thing was originally for use of the front ring of the original type of handguards. Not necessary for the nowadays free floaters in use.