"dislocation pileup" Found a small chunk of Cu/Sb alloy after hitting steel plate ~1700 fps. Shows the dislocation pileup or as I call it the pressure ridge wave (20x loupe). Looks like the teeth on a fine file, equally space ridges on ALL the surfaces of the chunk. No crystalline fracture structure, graininess, sheared or anything. No smooth mushroom (melted) looking surface. No good pics, she still hasn't learned to stay away from my desk when dusting.