Well, I can't speak for the manufactuing of munitions, but I can tell you about the automotive industry.. My company makes metal stampings, mostly for the airbag industry. In the automotive industry, "duds" are measured in PPMs - parts per million. Our customers, and indeed, theirs (the OEMs) want/expect a PPM of ZERO. In reality, a company is doing extremely well, if their PPMs are in the single digits (as ours generally are). "Bad parts" can be the result of dimensional issues, finish issues (i.e rust, plating, powdercoating, etc.), slug marks, scratches, bent, etc. etc. Usually, a bad part results in the entire lot (or lots) coming back, and 100 0r 200% hand-sorted, again. At our expense..
Now, I realize that to a degree, I am comparing apples and oranges, but one would think that similar, quality-related stipulations would be on hand grenades, or other munitions!!
???