I had a day off yesterday during which i waited for a plumber to come and give me an estimate for some work i need done. While sitting there I thought I'd sort some Lake City military brass -weeding out the scarred and badly dinged cases- to use in my new Ruger Precision Rifle. Digging around in the brass bins i found a sealed 2 gallon bucket with once fired, deprimed and polished Lake City brass from three different production years. Nice stuff! So shiny it hurt my eyes! I was struck by an idea. I went into the reloading Lab and brought out a digital scale and proceeded to weigh all the cases, setting each different weight into a separate plastic bin. I weighed all two gallons of brass. Normally I never weigh cases but I had time to kill. The results were startling.
Over the entire span, and discounting 2 cases that were outliers, I had just a 4 grain spread. If you can assume that they all started out with equal external dimensions, that would mean that the internal case capacity adjustment would equal just .3 grains of powder between cases at opposite ends of the weight spectrum. That's not too bad. Probably why I have gotten such fine accuracy using these cases over the years without worrying about the actual capacity of a case and just sorting by headstamp year of production.
The plumber never showed but I got 200+ cases of 'identical' weight to load in my RPR, with bags full of other weighed cases waiting. Stupid way to spend a morning but interesting use of it.~Muir
PS: Did I really spell 'military' with an e instead of an a?? Knot enuff coffey