[Adger Smith]

If you are not swinging the rods and weighing from end to end you are killing time. Assuming a set is equal on each end, big are equal as well as small ends, is a pretty big assumption. I've run into sets that are as far off as 7 or 8 grams. I think that is about the + or - for auto makers tolerance. Read a good tutorial about balancing before you start grinding on anything.
I bought my first balancer in 1977 and there is no telling how many mismatched components I've seen. If the rods were at one time a balanced set the resizing probably did take a couple of grams off the big ends.That happens on every set that is resized and all you can do is equalize them to the lightest one. Or if you want to cut the amount of change of the bob weight in half.... match a heavy rod with a lite one to make a pair.