A reticle of a projectile weapon aiming system such as a riflescope includes a primary aiming mark adapted to be sighted-in at a first selected range and further includes a plurality of secondary aiming marks spaced apart below the primary aiming mark. The secondary aiming marks are positioned to compensate for ballistic drop at preselected incremental ranges beyond the first selected range, for a selected group of ammunition having similar ballistic characteristics. Angles subtended by adjacent aiming marks of the reticle can be adjusted by changing the optical power of the riflescope, to thereby compensate for ballistic characteristics of different ammunition. In some embodiments, the reticle includes a set of windage aiming marks spaced apart along at least one secondary horizontal axis intersecting a selected one of the secondary aiming marks, to facilitate compensation for the effect of crosswinds on the trajectory of the projectile.