Don't care what bow ya got, don't care what poundage you got, don't care what arrow ya use. your not going to achive the above statement with a bow and arrow. Your key word is consistently.

Your are always going to get inconsistent results when you mess with the shoulder bone of any animal. Too many variables from shot to shot, anything can and does happen.

it is best to discover why your shots are going there, I know your not aiming there, and correct it.