An adjustable mounting system for a telescopic scope includes an adjustable elevation mount formed from a scope ring and an adjustable sub-base. A clevis portion of the scope ring holds an elevation pin that is received by a vertical slot in the adjustable sub-base. An internally longitudinal bore is disposed though the adjustable sub-base and an externally threaded barrel disposed in an opening of the longitudinal bore. A cylindrical elevation cam having an angled slot is disposed in the longitudinal bore and includes a positioning rod that extends through a bore disposed through the barrel. The angled slot receives the elevation pin as it extends through the vertical slot of the adjustable sub-base. The angled slot may be smooth or stepped. A bi-directional cam capture means is mechanically coupled to the elevation cam and provides for longitudinal displacement of the elevation cam through the cam bore. Detent mechanisms are incorporated in the cam capture means to provide audible or felt indication of elevation position. In various embodiments the cam capture means may be: a rack and pinion device operated by dial handle; a plunger attached to the positioning rod and extending through the rear of the sub-base, a lever attached to the positioning rod and extending through a notched slot in the side of the sub-base, a position dial including a dial thimble affixed to the positioning rod and threadably engaged with a barrel disposed on the sub-base. Other embodiments include a windage gib adjustably positioned in a bore of a lower portion of the sub-base and adapted to laterally offset the sub-base from the firearm rail.