I appreciate your question, Mark. I challenge guys on ethical hunting practices all the time and hold those ethics in high regard myself. Every hunter should.
I’ve done quite a bit of research on this. The magic number in terms of energy that most hunters will describe to you is 1,000 ft-lbs to bring down any big game. I shoot a 7mm mag loaded with 160 gr. Nosler Accubonds that retain 873 ft-lbs. of energy at 900 yards. That’s pretty stinking close to that 1,000 ft-lbs number and, I would argue, certainly enough to drop a whitetail.
However, in terms of ability, I’m not even near comfortable taking a 900 yard shot in the field, yet. I’m looking to get comfortable at about 700 yards at this stage in my life. With that, I’ve got 1182 ft-lbs. of energy. More than enough.
When I mentioned the 900 yard shots, I said hunters around here regularly talk about it. For instance, one hunter in our congregation shot a cow elk at 880 yards 2 years ago with his 300 win-mag. Dropped her right there. (Yes, there were witnesses). According to ballistics data reports, he only had 948 ft-lbs of energy, but I guess that elk didn’t study hard enough on what should kill her.
All that research I’ve been doing doesn’t just center around energy though. There are several other factors that come into play. Here’s a paragraph from one article I bookmarked a while back that makes a ton of sense to me:
“What kills animals is the terminal ballistics of a projectile. This is the tissue disruption and damage to the vital circulatory, neurological, or respiratory system of the animal. As an example, it is more ethical to hit a whitetail with a 225-grain Barnes Expander bullet, which has a mere 600 ft.-lb. of energy at 75 yards, than with a 500-grain solid from a .470 Nitro Express, which has 4,000 ft.-lb. of energy at that range. The superior terminal ballistics of the Barnes bullet will dispatch the whitetail more swiftly than the solid bullet will.” - Outdoor Life
There’s so much science that goes into a projectile.