I have opened HUGE holes in certain critters that DO NOT bleed externally. Their fat plugs the holes and you dont get no blood trails, pass throughs or not. Its fact of life. Fat and hair can plug holes and there be no trail. Maybe its just sitka
blacktails and elk, but I never seem to get much blood on the ground after wacking one. Lots of blood in the chest cavity though.
Put it in the right spot (like was mentioned B4) and you dont need a trail.