I dont have a spine tester, so I weighed all my bare shafts and seperated into groups. I have them in groups within 5 grains. 343 to 348, Next group is 369 to 374, etc... My question is this. Will the arrows within each group be close to the same spine? Would the arrows in the lighter grain groups have more flex and the heavier be stiffer? If so ,Can I adjust my tip weight to get them to fly the same? This my my first adventure into woodies and I want to do it correct the first time....Thanks Roy