Go with 100gr at that weight and speed you need the extra velocity to keep the arrow falling off at longer distances.

100, the lighter the better, my bow goes 315 fps.

CC

how heavy is your arrow and I will figure how much kinetic engery is with the 100 and 125's.

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.

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.

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.

You have to remember Zak, CC isn't shooting a real bow.

Dont say that on the Archery Forum. [:-]

Yes, I know she shoots a crossbow. A fast bolt is not necessarly better than a slow bolt.

My dislike of crossbows in the hands of able bodied people is well known, I've got no problem admitting it here or anywhere else.

Point being, Zak, the same concepts that we use with our bows and the equipment we choose won't necessarily apply to her.

Yes, but that little bit of information applies to her equipment as well.