Size is the reason larger shot are more likely to pass through, Michael. Increased size means increased mass and amounts to increased momentum. Increased momentum means a higher likelihood of a shot passing through, all else being equal.
Stan, you shouldn't have to say that. Some things are so rudimentary and obvious that they shouldn't have to be pointed out. But here we are...
I have often found even # 6 or # 5 shot embedded in the meat of pheasants, especially when shot from the rear at greater ranges. But I rarely bit into any, because the wound channel is evident and it is easy to find the pellet. But it is still prudent to chew gently on any bird killed with a shotgun, and especially game cleaned by someone else.
I haven't used # 9 shot for years, and never on game. I think it stands to reason that the low mass and greater pellet count per ounce is going to dramatically increase the odds of finding shot in your meat. I recall that i#9's seemed more likely to merely chip clay targets without breaking them than larger shot, but really smoked them with a good center hit at close range. I suppose it would be great on starlings or grackles at relatively close range.
That X-ray of the shot pellet embedded in your gum was impressive. A few inches higher and you could have been permanently blinded. If someone did that to me, I can't imagine not calmly walking over and knocking him out.
