I weighed 100 new Hornady brass (all the same lot). They varied from 52.46 to 51.76, that's .7 of a grain difference. Much better that what I have been using. I will do a volume check and let you know.
I did a little 17 Hornet brass measuring today and came up with some interesting information and here's what I got.
I took four pieces of once fired brass that was originally Hornady 20gr Vmax ammo, I took four pieces of factory loaded ammo from the same box, pulled the bullets, dumped the powder out and popped out the primers. This is Factory Hornady 20gr Vmax ammo I bought around 3-3.5 years ago. Then I grabbed four pieces of new unfired Hornady brass that I bought about nine months ago.
So I could get as accurate as possible I cleaned the primer pockets on the once fired brass and these were their weights with case volume, measured with water, in parentheses.
50.50 (14.85), 50.40 (15.00), 50.50 (14.85), 50.20 (14.90)
Then I measured the case weight and volume of the four pieces of loaded ammo where I pulled the bullets and dumped the powder. These came from the same box as the once fired.
50.25 (14.35), 50.50 (14.35), 50.40 (14.50), 50.50 (14.65)
Next, I measured the new unfired brass that I bought about nine months ago.
52.70 (13.90), 52.80 (13.85), 52.90 (13.90), 52.80 (13.90)
Granted, this is a fairly small sample size but the consistency appears to be pretty decent. I'd definitely say there is a certain amount of variance in this brass depending on when it was made.
Going forward, I'll certainly be keeping my brass from the shot factory ammo separate from the new unfired brass.