A drilling assembly for percussive drilling, comprising a drill bit and a drill rod ; the drill rod comprising a hollow elongate main length section extending axially between a male end and a female end ; the male end comprising a male connecting means and a radially projecting shoulder that axially separates the main length section and the male connecting means ; the shoulder comprising a peripheral surface having a greater outer diameter (D 1 ) than the outer diameter of the main length section (D 2 ), a first annular side surface that abuts the drill bit and a second annular side surface that flares radially from the main length section ; the drill bit comprising a mounting sleeve for connecting to the drill rod ; wherein the peripheral surface of the shoulder on the drill rod is at least partially encased in both radial and axial directions inside the mounting sleeve of the drill bit ; wherein the first annular side surface of the shoulder on the drill rod abuts an annular endmost surface on a connecting section of the mounting sleeve on the drill bit ; wherein the mounting sleeve on the drill bit the connecting section , has a first wall thickness (T 1 ) at its thinnest point, for securing to the male connecting means on the drill rod and an encasing section , having a second wall thickness (T 2 ) at its thickest point, for the shoulder of the drill rod to fit inside, wherein the second wall thickness (T 2 ) is less than the first wall thickness (T 1 ); characterized in that: the peripheral surface of the shoulder and an internal surface of the encasing section are substantially cylindrical; and wherein at least 20% of a length (L 2 ) of the peripheral surface of the shoulder is encased inside the mounting sleeve . the drill rod comprising a hollow elongate main length section extending axially between a male end and a female end ; the male end comprising a male connecting means and a radially projecting shoulder that axially separates the main length section and the male connecting means ; the shoulder comprising a peripheral surface having a greater outer diameter (D 1 ) than the outer diameter of the main length section (D 2 ), a first annular side surface that abuts the drill bit and a second annular side surface that flares radially from the main length section ; the drill bit comprising a mounting sleeve for connecting to the drill rod ; wherein the peripheral surface of the shoulder on the drill rod is at least partially encased in both radial and axial directions inside the mounting sleeve of the drill bit ; wherein the first annular side surface of the shoulder on the drill rod abuts an annular endmost surface on a connecting section of the mounting sleeve on the drill bit ; wherein the mounting sleeve on the drill bit the connecting section , has a first wall thickness (T 1 ) at its thinnest point, for securing to the male connecting means on the drill rod and an encasing section , having a second wall thickness (T 2 ) at its thickest point, for the shoulder of the drill rod to fit inside, wherein the second wall thickness (T 2 ) is less than the first wall thickness (T 1 ); characterized in that: the peripheral surface of the shoulder and an internal surface of the encasing section are substantially cylindrical; and wherein at least 20% of a length (L 2 ) of the peripheral surface of the shoulder is encased inside the mounting sleeve . the peripheral surface of the shoulder and an internal surface of the encasing section are substantially cylindrical; and wherein at least 20% of a length (L 2 ) of the peripheral surface of the shoulder is encased inside the mounting sleeve . <EOS>