So, I'm going to bring this thread back up. Just because I was playing around. Looking at the numbers and kinetic energy... With my current setup (70lbs, 363 grains, 308 fps) I am approximately 76.4 ft/lb of energy. If I go to a 125 grain tip (70 lbs, 385 grains, 298 fps) then I would be at 75.9 ft/lb of energy. So if you really look at it, the difference is almost negligible.
You are only looking at KE though. You are not considering momentum and FOC. The difference is there when you consider all aspects.
It's funny you say that, I was just playing with the numbers. My setup with a 100 grain tip has a momentum of 2.20 kg*m/s. My setup with a 125 grain tip has a momentum of 2.26 kg*m/s. Just playing a bit with another arrow setup I have (425 grains total): KE= 75.56 ft.lb M= 2.37 kg*m/s So which is better to have? Momentum or Kinetic Energy (work). Fun topic. If I use the 425 grain arrow it will slow down to somewhere in the 283 fps ballpark, but that is still plenty fast. However, you also see the decrease in your kinetic energy but increase in your momentum. If I have time at lunch tomorrow I'll try and chart some of this out.
Momentum is a measurement of force and it takes force to drive a projectile through a target, not work. I'll take the higher momentum every time.
If we're talking about rifle bullets, then KE is king. For arrows that move slower, they need momentum to drive them through the animal.
I'm going to play around with some numbers, just because why not I guess. A lot depends on the game you hunt. Obviously we here in the Midwest mainly get after whitetail and turkey that are rather small bodied animals. Therefore I would lean toward the speed aspect of it as opposed to the weight side of it.
In Colorado, I usually will be hunting elk and mulies at the same time. The seasons and the terrain coincide with each other. In Oklahoma and Texas I always used 100 grains. Here in Colorado, every broadhead I own is a 125 grain muzzy. Even all of my practice tips are 125 grains. I like to keep it simple and I know that it is a good setup for elk and that makes it plenty for deer or anything else I decide to hunt in North America.
With my arrows I wanted a bit more FOC but didn't want to stray from 100 gr tips. I went with gold tip arrows and put in a 20 brass insert weight that screws into the back of the insert. This gives me the same idea as a 125gr head while still being able to keep my 100 gr heads. For me, everyone I hunt with shoots 100gr heads and in general I find them easier to come across so this way I can borrow or lend a tip to anyone in my group without needing to re-sight in.
My GT XT 5577 arrows have a front-of-center of 10%. I like my 100gr Teken, so I an going to add 50gr weights to my inserts to see if the arrows group better at longer ranges. I don't know if it will work the way I want, but I don't mind tinkering to find out.
