Jim, I actually did spend an afternoon years ago shooting at targets behind bushes and shrubs and small branches. (!/4" or less.) I had a 45-70 with factory 405 Gr. flat points,; a 30-06 with both 180 grain softpoints and also some hardball ammo; and a 30-30. I was curious to see if the slow, large brush- bucking calibers myth was true. It wasn't
All three did fairly well on really soft obstructions like leaves but all three were randomly deflected to a considerable degree when I got to the sticks and branches. My target was a paper plate stapled to a tree, about ten yards past the obstructions. I can't really say the 45-70 was better than the others. With sticks and branches in the way, only about one shot in five hit the plate at all. There were no classic keyholes, but there were some elongated holes, indicating the bullet was yawing and not flying point first.
Obviously, the closer the plate was to the obstruction, the better the results. I am no hunter, but I think that shooting through brush is not a good idea, unless the animal is right next to it.