your bullet does this when it hits your deer. i shoot the same bullet except 130 grains in the .270 caliber. your 30-06 (hope i get this right) has more weight and is bigger in diameter so the mushroom will be bigger causin the hole to be bigger, the splitting of the bullet is probably from hitting bones and what not, the hole is actually good if you place the shot in the vitals like in that picture everytime, it more or less guarantees more damage caused by the bullet killing the deer faster.