Tumbling and fragmentation are both highly dependent on terminal velocity and the underlying stability of the round. For instance M855 will not fragment reliab

Tumbling and fragmentation are both highly dependent on terminal velocity and the underlying stability of the round. For instance M855 will not fragment reliably unless it hits ~2700FPS, which out of a 14.5" barrel gives you under 100 meters. In Mogadishu, M855 poked neat little holes, rather than tumbling or fragmenting, in Somali fighters with very little body fat. M193, which is obsolete for military usage but still the most popular bulk round on the civilian market, almost never tumbles in gel tests as it is overstabilized by the 1:7 twist, 16" barrels predominant in civilian ARs.