Here are a couple of links that might be helpful to you. The first is Jackson's web sight. Go to the arrow weight and FOC tool to calculate your arrow weight and FOC. I have found them to be very close.

[link]http://www.bowjackson.com[/link]

Next is a link to a source for some handy digital scales for weighing arrows and components. Check out the U.S. Bowhunter /US 100 model. It weighs in grains, grams,ounces and troy weight (drams) i believe. I think I gave about $40.00 for mine shipped

[link]http://www.perfectscales.com[/link]