Originally posted by Zradix: I agree with all above.I try to get em close..within 10 grains....but normally it's hard to tell the difference in up to 20 grains.What Pavan said has merit. But normally the little tiny bit of spine change isn't noticeable. I'd dare say if you notice a change after putting on similar weight broadhead you either didn't install it straight or your arrow spine was wrong to begin with and the BH is exaggerating the problem....or you may have to "adjust" your mind to the new sight picture.look up paper tuning..try it..it's super easy to do and it helps a lot.Doesn't have to be a fancy set up..I lay a 2x4 across a couple stools.Staple a piece of newspaper to it on the ends and middle.Put a couple spring clamps on the bottom of the paper to hold it down...shoot through it from about 5 foot...yes foot.