Btw, i see where the 450fps came from now.

First of all, IBO speeds are set at 70#, 30" draw length, with a 350gr arrow.

If bow A is rated at 330fps, and the archer is shooting a 350gr arrow at 70#, but only with a 27" draw length their calculated speed will drop down to 300fps roughly.

Sorry I forgot to explain where speeds are obtained from.

You can take this info now and apply it to any bow.

There is quite a but more depth in the subject, but this is a good foundation.

So, there is roughly a 2.5fps change per # and roughly 10fps change per inch of draw...how much change is there from arrow weight? Is that as simple an answer?

thats the best answer i seen bible man

1fps per 3gr

Roughly! Different for different bows and cam efficiencies. It is a dynamic change as well. As arrow weight goes up, dynamic efficiency goes up so it will take more gr to lose 1fps.

Simple, not exactly, but close enough

I did not know that. I kinda figured length had some to do with it but was stunned to find out its 10 fps faster per inch. Thanks for the Info. drockw

lol, Sorry guys didn't mean to start something, Well I have a longer draw length.. lol
But What it comes down to it, well what I thought was right,. I just wanted a second notion to what I thought.. But drockw does make since and I do understand..lol Thanks everyone..