In this paper, we extended our work on RDX and TNT‐based explosives to lower diameter to validate detonation shock dynamics (DSD) first‐order relationships between normal detonation velocity Dn and detonation wave curvature κ. At 25 mm diameter, we observed that Dn–κ relationship approximates, although not perfectly, the relation for 50 mm diameter. Thus to an approximation, the first order DSD theory is independent of geometry. On that basis, a general equation has been proposed, which can predict Dn–κ for RDX/TNT cast explosives in the mixing ratios 60 : 40–40 : 60.