Here's one for the OCD crowd.
A while ago there was a thread on shaving the bases of cast bullets, i.e removing lumpy sprues and generally flattening the bases, mainly to make a better seat for the gas check.
Generally I don't bother shaving plain base bullets. If I can see a lumpy sprue when I open the mould I just dump the bullet - I can make a new bullet in less time than it takes to clean up a lumpy one.
I do however shave/scrape the bases of #U321297HP bullets (.322") that I turn into .30-30s (.312"). Sizing down a .32 gas check to .30 results in a concave dimple in the gas check. If the bullet base is clean (shaved), the dimple will be centred. If there is a some lumpiness or cratering around the sprue the dimple may be misshapen and off centre. I shave all the bullets, not just the obvious ones. The tool is a sharp knife, and I try to get just the sprue material.
Variable sprues also feed into variable bullet weight. I sort my bullets into weight groups, although mainly I'm after the light ones that might have a hidden flaw or the heavy ones that were made with the HP pin not fully engaged.
I also use my bullet weight to confirm correct alloy, so differences from shaving if substantial would come into play.
Out of interest I weighed the material that came off a recent run of #U321297HP. Total weight of scrapings was 27 gns off 269 bullets - 0.1 gn per bullet. Doing the weight grouping after rather than before shaving seems a viable choice.
I should say that all but a few of my sprues are pretty good to begin with, but scraping makes them better.
You are only as good as your library.