ORIGINAL: huntIL104
I would go with the 100 grain because you will get better speed and distance with them. I work at a archery shop so there is my 2 cents worth take for what it is worth.
Although that is correct, it is not the right answer. You will be able to shoot faster and farther with a 100 grain head, but you may not be accurate. If your arrows are severly overspined then you should get a 125 grain head. Also you will not notice a distance change with 25 grains. Although there is one, you won't be able to tell. Plus by shooting that extra 10 feet won't help you bag that deer.
ORIGINAL: Canadian Chic
100, the lighter the better, my bow goes 315 fps.
That is not even close to being true. With a light setup you need a heavier arrow which will give you more momentum. This will help the arrow penetrate deeper.
ORIGINAl: pe-archer
how heavy is your arrow and I will figure how much kinetic engery is with the 100 and 125's.
Your KE will not vary much when you switch to a heavier arrow. If you shoot a 400 grain 250 fps you will have 55.53 KE. If you switch to a 300 grain arrow, or a 500 grain arrow your KE will only vary by a few lbs. The only way to raise your KE is to increase the speed, but you cannot do it by shooting a lighter arrow. By using a broadhead 25 grains heavier will make absolutly no difference to the archer.