ive seen topics about something called FOC, and was wondering what it is and how you determine it?

A great site to get your answer as well as figuring your FOC out for you is www.bowjackson.com. It also has alot of other interesting and helpful info.
Hope this helps. Good luck.

k i just calculated it, and it says i have a 7.8% foc. i dont think that thats good. ive heard between 12 and 15 is desirable. am i wrong?

im running 27 inch Redhead Carbon Supreme 250s with 85 grain Thunderhead broadheads and plastic vanes(not feathers). what do i need to change?

Huntman,
I am definitely not an expert in the subject but do put some stock in Bob Ragsdale who was a design engineer with PSE for many years. He has a Q&A on the topic. If you would care to read it here is the URL. http://domino.htcomp.net/ragsdale.ns...ighlight=0,foc . I can tell you that he puts no stock in the concept. Hey man he knows more than I do but he still might not be right. Read what he says and decide for yourself.

Hey, size may not matter but it sure IS nice!

huntman,

If your arrows are flying well, I would not be too concerned with a 7.8% FOC. Remember to increase your FOC you will have to increase tip weight which will weaken your arrows spine. Depending on the spine of your arrows that may or may not cause problems.

Aim Hard!

hmm my only concern is that i havnt shot my broadheads before, because i dont have a broadhead target, and my parents are too cheap to buy one, so i dont really know how they fly with the broadheads.

Huntman.

I dont think I am all that far from you.
If you like we could arrange a date and time and you could come over and test shoot your broad heads at my place.