I have been shooting both Hornady and Speer balls for many years and have never seen the fragmentation you report. My experience is the ball passes through intact.
Really old Bob is right about the variation in Hornaday balls. In my experience, Speer balls have less variations in weight.
IMHO, target shooters should weigh every ball they shoot, whether cast or swaged. IMHO, the weight variations don't appreciably effect hunters and fun shooters. Minute of squirrel at 30 yards is good enough for me. :v
J.D.