Because they spec'd that bullets should penetrate at least 12" and no more than 18", and that penetration over 18" was a failure, or at least scored lower. The 70% miss rate as far as shooter accuracy goes is a little bit misleading, since, in my experience, LEO's with high capacity magazines will tend to fire more rounds as suppression fire at fleeting targets, such as targets that are difficult to see, like targets crouching behind a car or other cover. So, if 70% are misses, why limit the penetration requirement to 18" if so many bullets are going to be misses, anyway? Who knows if they extended the penetration limit to 20", 24", or unlimited, if the bullets with greater sectional density or weight would begin to show an advantage?
