Great analysis. I am interested to hear what conclusion you came to as far as total arrow weight, broadhead selection, etc. You sound like you have a lot of years worth of data points to look back on.To the basic question of what causes wounding loss I think it is lack of penetration, sharpness / durability of the broadhead and shot placement. None of these guarantee success as they all have to work together for us to achieve success. You can make a perfect shot with no penetration or have a dull broadhead, or get full penetration in something not vital. Blood trailing is another problem if there isn't one to follow.
My story of wounding loss and my full circle
I kept notes from old arrows from years gone by and thought I would share some lessons I learned over the years. During my early bowhunting career (1979-1985) life was good and no animals were lost according to my notes. Three elk, four deer and a bear were harvested. I kept each arrow recovered for years and documented from which animal and their weight. Those early years started with Satellite 125 grain four blade 1" razor blade broadheads, XX75 2216 shafts, 72 lb. draw weight with a forgiving round wheel compound bow, shooting fingers with a tab at 202 fps.
Following my early success I began changing things to follow the crowd and the marketing hype (1986-2020). New cam bows, lighter and lighter aluminum arrows, heavier 150 gr. broadheads then lighter 100 grain broadheads, mechanical broadheads, carbon shafts, full metal jacket heavy shafts, new releases and my list could go on. As I made these changes and my wounding rates increased, but accuracy improved in practice. I thought it must be my shot placement on animals (which looked good), or maybe my broadheads were causing the problems. I wondered why better shot placement and faster arrows were leading to fewer recoveries. Not every shot was perfect, but I noticed penetration was decreasing and animals living longer than what I had come to expect from those early years. I also noticed deflections were becoming more and more common which I hadn't seen before.
Over 40 plus years, I have lost five elk (only one I believe was because of shot placement) and three deer. Plus some additional stories of long tracking jobs with antelope in open country. About three years ago I sorted my arrows by years and noticed overall weight had been steadily declining over the years by 200 grains. I knew that lighter weight arrows allowed me to have more pins and more pins meant I could shoot farther. However in actual hunting situations I never shot much farther than I had earlier. I gradually started passing good shot opportunities because I had lost confidence in my setup even at close range and just took a picture to share with my buddies who thought I must had joined PETA.
Three years ago I decided I needed to figure out why my old system worked so well, before I quit bowhunting. I decided to learn about arrow lethality and make whatever changes were required using my old system as a base example. I wasn't sure I believed everything I read and heard but thought I would give it a try before my bowhunting career comes to an end. I didn't follow everything I learned that first year, but I was willing to try it and as luck would have it I did harvest a bull elk that first year and everything was different. It was different than anything I had ever experienced before and it was like my arrow was on steroids just passing through an elk. Second year I moved up a little more in weight and FOC and again everything was different just like the previous year. What I mean by everything was different was arrow flight, penetration, broadhead sharpness, reaction to the shot, tracking distance etc.. Shot placement was okay on a quartering in and better on quarter away. But the reaction to the shots were totally different. Both bulls jumped at the shot/impact, then walk a short distance, stood still then fell over within sight. Much better than old system. No tracking was required on either bull and penetration was complete and total pass through. Previously I only had one total pass through on elk in forty plus years of bowhunting.
I realize my sample is only two elk, but I only get one tag per year.
Good luck to all,
PM me if you have questions