Hornady brass weight differences

[bdubmkg]

Last night I was loading some 6.5cm and I decided to see how much difference there was in the weights of each case. All hornady.
Most of the brass hovered around the 158 to 160 gr area but had a decent amount of them that were in the lower 150s.
It got me thinking, how much does this affect round consistency? I would think it would if you have a case that's 8+ grain weight difference.

 

[Old Man with Gun]

I weigh mine and there is higher velocity with heavier brass and better SD when I batch them by weight groups.

 

[straightshooter1]

Last night I was loading some 6.5cm and I decided to see how much difference there was in the weights of each case. All hornady.
Most of the brass hovered around the 158 to 160 gr area but had a decent amount of them that were in the lower 150s.
It got me thinking, how much does this affect round consistency? I would think it would if you have a case that's 8+ grain weight difference.

Since there is certainly some correlation for a brass weight and its case volume, a significant difference like that can indeed affect consistency for velocity and on target. I've tested this by weighing my Lapua brass comparing those that were the most light to the that were the most heavy. Culling out the outliers can help with getting better consistency (lower ES's and SD's).

I weigh mine and there is higher velocity with heavier brass and better SD when I batch them by weight groups.

Yup, the heavier brass tends to have less volume, which will increase velocity given the same powder charge. I too like to "batch them" after culling out the outliers, which I found helps a lot in getting lower SD's and ES's.