Daniel, no I have not tried the 3M Sandblaster but will get some for overall sanding anyway. It is a good alternative. On the spine differential, most of my arrows are weighed and spine is very close. The spine is + or - 3# and the weight is within 25 grains, total arrow weight. I separate them in groups of 6 arrows. The loss in spine averages about 1 to 1 1/2# on 31 inch shafts centered at 26". If I move the shaft to the nock, it looses no more than 1/2 #, additional. That is an average. Hope I answered your question.
Dick