RE: Spine adjustment?
 

As for the differential in arrow weight, this is negligible on 20 and 30 yard shots and for a hunting setup there is little concern. It's when you shoot competition at longer yardages that the weight becomes a critical issue. I assemble my own arrows with each being cut at precisely the same length with all components identical. I'll then weigh all the completed arrows, without tips, and find the lightest. Then I screw in the tips and check the weights again using the lightest as my base. I'll grind the base of the tip until it matches the lightest completed arrow and do this for the entire dozen. Each arrow is exact in spine and weight. This will make a substantial difference in accuracy and tuning even on close shots. The length of the arrow effects spine. The longer the arrow the weaker the spine or the more the arrow will flex on release. In turn, a shorter arrow will stiffen spine. One helpful hint is to make sure your arrow is long enough so that the insert that holds your tip is NOT on the rest. If your insert rests on the rest or cushion plunger for fingers shooters it deadens the rest or plunger. Make sure you have at least 1/2" of the insert in front of the rest prongs or cushion plunger.;)

RE: Spine adjustment?
 

God bless this forum. Ten years ago who would have thought some much information could be available so quickly and cheaply.

Thanks everyone.

RE: Spine adjustment?
 

If you reduce the tip weight by grinding it, the effective spine will be stiffer. Although they may fly very close to the same, the spine would not be exact on each arrow. In addition, each arrow starts out with variable spine within the group. So, although you can get weight to be very close to exact, matching spine can be very difficult - especially on some arrow brands. To match spine to even a somewhat close measurement, you'd have to pick arrows with very consistant spine on each side and them cut shafts until you had matching effective spines. I don't even know how this would be measured unless you devised a spine tester that had a movable end-support, so you could test each arrow with the ends resting on the supports.

If I had an arrow that measured .330 spine and another in the group that measured .340, the stiffer arrow is also likely to the heavier one. Cutting the heavier one, will make it even more stiff, resulting in even greater spine variation among the group. If you're shooting the whole group on the stiff side, then flight differences (with broadheads) might not be that great, but if spine is borderline, then fairly large variation in flight may occur.