Burris Burris Medium Extension Rear Only. New Old Stock. 420061. PreviousBurris Ruger M77 Gloss Black Scope Mount Rings. NextBurris 1" CZ 527 Rings. Medium, 420140. Burris Medium Extension Rear Only. New Old Stock. 420061. Burris Medium Extension Rear Only. New Old Stock. 420061. $49.00 Add To Cart Facebook0 Twitter