While it feels good to debur the flash-holes, is there any EMPIRICAL evidence to show it makes an actual, repeatable difference in vertical at long range?
How much of case prep has an actual impact on accuracy and how much is for "piece of mind", for the type of shooting we engage in?
Like other 'endeavors' there is an aggregate that has to be considered. Taken solely, each step is probably hard to quantify, but taken as a group of steps, there can be measured gains.
The problem with burrs on flash holes is, is that once you remove them, you can't really go back and do an A/B comparison. I do think that there is a point of diminishing returns, for me at least and that's why I'm not turning my necks and water weight sorting brass. I've done some of those things, but for me, it's not worth the time.
Uniforming primer pockets and deburring flash holes takes so little time and physical effort (with a power drill/Trim Mate) that it's something I don't fret over too much.
Others will obviously not share this thought, but it 'can' be the little things that add up to noticeable gains, is my thought.
Think about it? Why weigh down to .02 of a grain? That's outside the accuracy parameters of most all chronographs, so you're not going to be able to measure that with any certainty, yet people ANALyze over it.
Wet tumbling? Look at the loons rushing out to play with muddy water around electricity. You think that shows up on the target?
People do what they do and we just learn and adopt, or move on.
Chris