WTB: Mk18 RIS, low profile gas block Aug 19, 2012 3:54:42 GMT -5 Quote Select PostDeselect PostLink to PostMemberGive GiftBack to Top Post by warlord on Aug 19, 2012 3:54:42 GMT -5 As the title states im looking for a Mk18 RIS and a low profile gas block.Dont care about brand of the gas block.The rail can either be the KAC style or the DD full length.