I'm wondering which is the correct way to measure an arrow? From the end of the shaft to the end of the nock or to thegroove in the nock. I've heard of it measured both ways.

Yep so have I. It's good to clarify with someone your doing business with how they want it done. I measure the whole thing for everything, cutting and foc calculations. (I cut my own)

AMO standard arrow measurement is taken from the groove of the nockto the end of the shaft.

You want to measure your arrow from the groove in the nock, because that is where the string hits the arrow. You usually want your arrow about a half inch or so over hanging your rest.

Correct and arrow saws are set up this way.