Re: Case head squaring
You pose some excellent questions! After doing all the match prepping you talked about, including case "perpendicularity" (I love that word, it makes us sound so smart!) the brass weight spread went from 1.2 grains to 1.6 grains high to low. So it did make some difference for sure, but it still was pretty insignificant. I could still tell that it was great brass. Now, I will tell you upfront that I have only done this trick to Lapua BR brass, so I don't know about the other kinds of brass. 7MMRHB could tell you way more about it than me. I can tell you that it would be a possibility to weigh the brass before and after you cut it. Then you would know if it is a variance in volume or just machining shavings. On that one case out of 200 that was .006" short in the neck, it also weighed less but I knew why because I measured it and just kept track of it by putting a notch in the head.
As for your last two questions, the degree of how much square/flat there is seems to be more than I thought it would be. Up until this experiment, I kinda thought that it would be pretty insignificant, but as I finished up the 200 rounds of excellent brass, I looked down at the pile of shavings that came off those heads and now I would have a hard time NOT doing this given my perfectionist mentality.
And yes, it seems that once it is fired many times in a blueprinted action, it remains very constant. In other words, it is a one time deal like flash hole deburring.
good shooting! -goodgrouper
If it's not far, it's boring.