I responded to this request yesterday, but somehow missed the fact that you are shooting Gold Tip arrows. Here's one way to achieve your desired 620 gr arrow. I'm sure there are many, and you'll have to decide which one gives the best performance out of your bow.
I'm guessing you shoot the 3555 spine, but if you use the 5575 shafts, you can make similar calculations. And when all is said and done, you may want to adjust the length or point weight to get an arrow that flies great from your bow. Anyway, here's one approach:
I shoot an arrow about 1 inch longer than my draw length, but to get the weight you desire, you may need to go a little longer. Let's say you start with 27.5 inch, that shaft should weigh approx. (27.5 inch x 8.6 gr/inch) 236..5 gr. Now, add approx. 25.5 in of 8 gr/inch weight tube ( 3 Rivers # 6731X ) to give 205 gr. I approximated the shorter weight tube compared to the shaft to allow 1 inch on either end for point insert and nock. Now add approx. 11.4 gr for insert, 12 gr for nock and 10 gr for fletching and glue. That gives a fletched shaft of (236.5+205+ 11.4+ 12+10) 474.9 gr. A point or broadhead of 145 gr brings the total arrow weight to 619.9 gr. Small adjustments to shaft length, fletch weight, etc can be accommodated by making compensatory changes to point weight or whatever. You can make similar calculations for the 5575 shafts if they work better for you.
I hope this is helpful.
Answered on 2/26/2013 by Anonymous