- Jan 5, 2004
Once you decide you want truly accurate ammo, you will buy batches of cases from a single lot. Until then, you are hoping for similar brass.
I think the "weight sorting doesn't matter" logic relies on the assumption you're using cases from a single lot of brass that you have some kind of history on. Case capacity is more important then weight sorting inside a lot. If you have a bunch mixed you'd have to weight sort, then volume sort. If you haven't deprimed yet start checking some with water.
Hornady once fired brass is really bad for this, I don't know if the Hornady bag brass is any different I started loading 6.5creedmoor with 100 pieces of S&B brass and 120 pieces of Hornady once fired brass from ammo I bought. Originally, being a newby I assumed that the Hornady brass would be best because they had a large online presence in the reloading and precision shooting community. I was wrong, not saying if you buy a bag of Hornady brass or bags all from the same lot you can't get good results. But after wieght sorting the brass I found that while the S&B brass had an extreme spread (brass wieght) of 3 grains and the Hornady brass had an extreme spread of 12 grains. While I know that internal volume and wieght don't always correlate, a variance of 12 grains either way (and this was not just outliers) most likely would have significant impact on my internal volume, groups and definitely velocity. I did figure out however that if you get Hornady brass all from the same lot it is very close to the same. The problem arises when you have 20 pieces from American whitetail, 30 pieces from 2 different boxes of Precision Hunter and 50 pieces of American Gunner.First time loading for 308. Got a pile of once fired Hornady Tap brass for pretty good price. Long story short. Spent over 300 rounds fighting 5 shot groups that had 3 and 2 together or 4 and a flier, cussing my chronograph, and scratching my head at random pressure signs showing up. Turns out Hornady changed their match brass at some point. I have some that weigh right at 160 gr. Some right at 172 gr. And a handful of regular head stamp Hornady at 190. All mixed together when tumbled and pulled back out in random batches. Go me.
Your chamber has a fixed volume. Fill it with 160gr of brass(in any shape) and it’s volume is reduced. The very slight differences in density of different batches of cartridge brass is minuscule. For the purpose of this, the chamber ends as the base of the bullet, so the neck beyond that needs to be similar on all the cases being weighed. You’ll get good results if you have them all trimmed to the same length before weighing. You’ll get better results if the necks are all turned to the same thickness.You really need to check capacity. Different brands of brass have different brass thickness so weight is a moot point. The best thing is to purchase good brass to begin with and you will have less fustration. There are some good posts on this forum to explain. Just do a search on Brass H2o capacity.
Yes it will take a lot of time to volume weigh the cases. You can go to "H20 brass on the internet. There quite a bit from Accurate Shooter about volume weight.Your chamber has a fixed volume. Fill it with 160gr of brass(in any shape) and it’s volume is reduced. The very slight differences in density of different batches of cartridge brass is minuscule. For the purpose of this, the chamber ends as the base of the bullet, so the neck beyond that needs to be similar on all the cases being weighed. You’ll get good results if you have them all trimmed to the same length before weighing. You’ll get better results if the necks are all turned to the same thickness.
There is no reason to attempt to directly measure volume. It’s time consuming and prone to error from air bubbles and variance in menisci. An unfired case will have less volume than a fired case, but it expands to fill the chamber so easily that it has very little effect on pressure...only on how much powder you can fit in the case.