The spine, rather than the manufacturer, is really what you need. Find someone with a spine tester and measure the spine, then measure the o.d. Then, of course, you'll need to find an arrow with the same static spine and o.d., cut it to length and then figure out the tip weight (including insert) of the one you have now. Here's where you want to weigh both arrows. Subtract the weight of the new arrow (including nock and fletchings) from the weight of the old arrow and you should have the weight of the tip and insert. Install tip and insert of that weight. Fletch it, install a nock and there you go! Nothing to it. Shouldn't take more than a week or so!!