5.56 77GR Bone Frog Ammunition® Sierra Tipped MatchKing (TMK)(B556TMK77)5. 56 77GR Bone Frog Ammunition Sierra Tipped MatchKing (TMK)(B556TMK77) Sierra has enhanced a segment of the MatchKing line by adding the acetal resin tip, thus crowning the Tipped MatchKing (TMK) bullet line. The major advantage of adding a tip to the bullet is the reduction of drag, producing a more favorable ballistic coefficient. Another benefit is reliable feeding in magazine fed firearms. The 77 grain Tipped MatchKing (TMK) allows seating to an