Case weight variation

[rodell]

I've never paid much attention to case weight (primary interest is hunting, but I always strive for smaller groups) but I decided to weigh a series of 300 Weatherby cases due to another problem I was researching. Unfortunately, I didn't keep my cases separated by lots.

I got a range of 216 to 233 grains, with a bimodal distribution around 218 grains and 224 grains.

What do those who sort their cases by weight accept as variation? What do you do with the outliers?

 

[Elkman]

6 grains seems like a lot, i like to keep mine within two or three grains of each other. What is your median weight? I would separate them into two groups and would test for accuracy with each separate group. Those well outside of both groups i would smash and put in my brass, trash bucket. I would keep them separated from now on.

 

[Rol_P]

I found a significant variation between two lots of Nosler 30-06 brass. Within lots the variation was generallly +/- about 0.2 of a grain. The variation between lots was closer to 9 or 10 grains, but again within the heavier lot they were very consistent. Looking at the head stamp indicates a clear difference in the stamping, and a suspected different vendor manufacturing. I can not say with certainty that the difference affected my groups or changed point of impact, but suspect that the heavier case, with equal exterior dimensions would have a smaller internal capacity therefore resulting in a slightly higher velocity. Ammo loaded with the heavier cases are marked as such to keep them separate.