Miller was quite correct when he spoke of seam defects in steel. That is just one of many internal defects that can and do occur in modern fluid steel. There are laps, cracks, porosity, rolled in slag or scale, slivers, other impurities and inclusions, alligatoring, etc. Generally, under the enormous forces of hot and cold rolling, these defects become very much elongated as Bill Schodlatz mentioned earlier. I recall a guy showing me this by tossing a copper penny onto a coil going into a five stand Tandem Mill where the rolling tonnages were around 800 metric tons force on the rolls. The penny ended up as a copper colored smear several feet long and rolled into the surface of the steel.
As such, we are probably getting way out in left field when it comes to what caused the burst in Rob't. Harris' friend's Beretta since such defects are typically longitudinal, and therefore will not develop ring bulges before they finally rupture. The questions here are... what was the obstruction, and was the bulge from that enough to cause a second obstruction in the top barrel, and why did the top barrel unintentionally fire?
But I always get a kick whenever we have a discussion on the safety of shooting Damascus barrels. Inevitably, one or two guys always chime in about the extreme danger of shooting those old tangled masses of welded strips of iron and steel. They seriously think their modern fluid steel is some perfect homogeneous structure. Overall, it is pretty good stuff. But they really ought to take a minute to Google "internal rolling defects in steel" and look at some of the images they will find. Or maybe ignorance is bliss, and we're all very lucky.
