I think this is a good read.
Gillingham really knows his stuff
This is from the gold tip website
"Do I need a heavy arrow for hunting out west?
No not really. More elk and mule deer are harvested every year with a 5575 in their lungs than just about any other arrow size. Weight does not necessarily mean penetration. I would categorize the following things to be most important for penetration.
Shot placement is number one. You hit the animal in the right place it will go right through. If you hit the opposite rib dead center at 50 yards on an elk, you probably wont blow through even if you are shooting 80 foot pounds of energy and a 430 grain arrow. Set you bow up with a reasonable amount of speed that will help with yardage errors. That will be the biggest factor for great penetration and good shot placement.
If you are going to change anything from your deer hunting setup to your elk hunting setup, change your broadhead. Use a broadhead that is more sloped and uses a less choppy action of cutting. Although many kill elk with 2” cutting diameter broadheads, being a little more conservative and option for 1 1/8” to 1 3/16” is a little more realistic for reliable penetration.
Good arrow flight is paramount for good penetration. Loss of energy due to the arrow striking the animal any thing less than perfectly square will result in penetration loss as the energy is not expended directly down the center of the shaft. Make sure you bow is paper tuned very well and your shooting skills up to par.
Weight consider for me is only a happy medium. I like a 400 grain plus arrow but mainly to help with longer range accuracy and shooting in the wind. I would not shoot my bow below 280 feet per second just to make sure I shoot the magical 400 grain arrow. I would go to a lighter arrow or a faster bow."
My take home from this. Make sure your arrow flight is perfect.
I shoot a 428 grain arrow at 284 fps
