An indexable, single-sided cutting insert comprising: opposing upper and lower surfaces (22, 24) with a peripheral side surface extending therebetween and a central axis (Ac) passing therethrough, the upper and lower surfaces (22, 24) having shapes that differ from one another; first and second clamping bores (28a, 28b) extending between and opening out at the upper and lower surfaces (22, 24), the first and second clamping bores (28a, 28b) having first and second bore axes (AB1, AB2), respectively; and first and second primary cutting edges (30a, 30b) formed at the intersection of the upper surface and the peripheral side surface; wherein the lower surface includes: a planar base surface, first and second annular recesses (36a, 36b) communicating with the first and second clamping bores (28a, 28b), respectively, and first and second recess channels (44a, 44b) extending from the first and second clamping bores (28a, 28b), respectively, to the peripheral side surface, the first and second recess channels (44a, 44b) extending parallel to a longitudinal first plane containing the central axis (Ac), wherein the first and second annular recesses (36a, 36b) intersect first and second bore neck-portions (40a, 40b) of the first and second clamping bores (28a, 28b) at first and second minimum bore diameters (DBMIN1, DBMIN2), respectively, and characterized in that: the first and second annular recesses (36a, 36b) include first and second annular shoulder surfaces (38a, 38b), respectively, the first and second annular shoulder surfaces (38a, 38b) intersect the first and second bore neck-portions (40a, 40b), respectively, and the first and second annular shoulder surfaces (38a, 38b) are coplanar and perpendicular to the central axis (Ac). opposing upper and lower surfaces (22, 24) with a peripheral side surface extending therebetween and a central axis (Ac) passing therethrough, the upper and lower surfaces (22, 24) having shapes that differ from one another; first and second clamping bores (28a, 28b) extending between and opening out at the upper and lower surfaces (22, 24), the first and second clamping bores (28a, 28b) having first and second bore axes (AB1, AB2), respectively; and first and second primary cutting edges (30a, 30b) formed at the intersection of the upper surface and the peripheral side surface; wherein the lower surface includes: a planar base surface, first and second annular recesses (36a, 36b) communicating with the first and second clamping bores (28a, 28b), respectively, and first and second recess channels (44a, 44b) extending from the first and second clamping bores (28a, 28b), respectively, to the peripheral side surface, the first and second recess channels (44a, 44b) extending parallel to a longitudinal first plane containing the central axis (Ac), a planar base surface, first and second annular recesses (36a, 36b) communicating with the first and second clamping bores (28a, 28b), respectively, and first and second recess channels (44a, 44b) extending from the first and second clamping bores (28a, 28b), respectively, to the peripheral side surface, the first and second recess channels (44a, 44b) extending parallel to a longitudinal first plane containing the central axis (Ac), wherein the first and second annular recesses (36a, 36b) intersect first and second bore neck-portions (40a, 40b) of the first and second clamping bores (28a, 28b) at first and second minimum bore diameters (DBMIN1, DBMIN2), respectively, and characterized in that: the first and second annular recesses (36a, 36b) include first and second annular shoulder surfaces (38a, 38b), respectively, the first and second annular shoulder surfaces (38a, 38b) intersect the first and second bore neck-portions (40a, 40b), respectively, and the first and second annular shoulder surfaces (38a, 38b) are coplanar and perpendicular to the central axis (Ac). the first and second annular recesses (36a, 36b) include first and second annular shoulder surfaces (38a, 38b), respectively, the first and second annular shoulder surfaces (38a, 38b) intersect the first and second bore neck-portions (40a, 40b), respectively, and the first and second annular shoulder surfaces (38a, 38b) are coplanar and perpendicular to the central axis (Ac).