Shoulder angle and elbow angle are important for sure. If my right shoulder is not in the correct spot it forces my right elbow up and out and I'm inconsistent. If I "lock" the shoulder into the right place everything comes together and I punch centers. i too have a problem with my right shoulder feeling tight and that's usually what causes me to push the elbow out. not good at all.

Indians didn't sit around thinking about the FOC of their arrows. Studies where not done because most people have the common sense to realize that they needed to use heavy tips back then to get penetration with their slow arrows. Once arrows got faster there was less need for heavy tips. Lot's of people experimented with very heavy tips way before Ashby did his report. you will not find the reports probably because they are never published or done before the INTERNET became so popular.