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 (24, 24') of the shoulder (22, 22') 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 (24, 24') of the shoulder (22, 22') 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 (24, 24') of the shoulder (22, 22') is encased inside the mounting sleeve.