If just shooting still targets energy really isn’t a big deal. It might make it harder to ringe the target though. Now shooting a live target such as animals. Now that’s a hole different ball game. I agree with you. If you are shooting live animals You not only need to know you can hit your target but have enough FPS for the bullet to expand properly and have adequate energy for what your hunting. That’s where everything gets complicated. When I have helped people about this some interesting thangs come out. Many people just say get a big heavy bullet and you’ll be fine. I tell them it’s a little more complicated than that. Read the box. Research the bullets your using. If it’s a top grade bullet that is designed for long range hunting it will tell you the minimum FPS the bullet needs to travel for it to expand properly. I have some Berger’s for my 260 Rem ( 140 grain VLDs ) they are I guess the first gen VLDs. On the box it says my BC is .612 and they need a minimum of 1300 FPS to expand. I have some other 140 grain Berger’s VLD ( 2nd Gen ) and they say the BC is .600 and that they need 1600 FPS to expand. I don’t know what Berger changed or if it was a misprint on the box but I use the fist Gen data and it all seems to work fine for both. When I shot my cow elk in Colorado at 1105 yards the people I was hunting with said I was way under gunned. I used my JBM calculator and it said I would still be at 1950 FPS and 1200 lbs of energy. We were around 8,000 feet above sea level. Again this is where it gets really complicated. Some people say you need 2,000 lb-ft others say 1,500 lb-ft of energy for a elk rifle. My theory is 1,000-1,200 lb-ft for elk. Now why do I thank that? Because I brought my elk home. I tried to find my bullet but was unsuccessful. I know it expanded properly do to all the Trauma inside. What has worked for me is 600 lb-ft for deer 800 lb-ft for mule deer 1,000 lb-ft for elk and 1,200 for moose. This is just what works for me. This is my theory and it has not let me down. So as long as my FPS is a min of 1,300 FPS and what I thank is enough energy for what I’m hunting I’ll keep using it until it fails me. So far so good. Again this is just my theory and I have tested this in the field myself.