Questions about Weight-Sorting Cases

[dgeesaman]

I'm prepping new cases for my 6.5x55 and have chamfered the flashholes, trimmed them to the same length, and neck-turned them. These are Lapua cases, and I weighed 40 and found them all to be within about 1 gr. in weight--from a low of 176.8 gr. to a high of 177.9. I thought I'd sort them into two groups--the lightest 20 and the heaviest 20. If I do it this way, the weight variation in each group of 20 will be about .5 gr.

Here are my question:

1. Is this sorting worth the effort? To be sure, it didn't take much time, but if I passed on the sorting I'd have cases varying by up to 1 gr. in weight in groups shot.

2. In my two groups of 20 cases--with the variation in each of the two groups of 20 cases running .5 gr.--is this sufficient closeness in case weight for you guys shooting competitively? That is, in any group of 5 shot, the maximum case weight variation would be .5 gr., and in some groups shot, it would be less than that.

I did the exercise of sorting brass by weight, by internal volume, and by both. 6BRA and Lapua brass.

I found no correlation to velocity. That’s not to say it cannot exist, and surely with enough variance it will, but in my experience it’s a fairly fine variable and it’s effect can be negligible in many cases.

David

 

[6bra1k]

I did the exercise of sorting brass by weight, by internal volume, and by both. 6BRA and Lapua brass.

I found no correlation to velocity. That’s not to say it cannot exist, and surely with enough variance it will, but in my experience it’s a fairly fine variable and it’s effect can be negligible in many cases.

David

what was your weight separation..in grains

 

[dgeesaman]

what was your weight separation..in grains

It was Peterson 6BR brass, not Lapua. 133.75 min 135.3 max. Water volume ranged from 37.77 to 38.02 gr.

 

[Fuj]

I'll throw this out for constructive arguments sake. Take a 6PPC
case and set it next to a 284 Winchester. Which case in your
opinion would benefit most from a weight sort, and knowing
one is use for short range and one for long range competition ??

 

[ronemus]

Brass used for short range (<300 yd) doesn't need to be sorted by weight or volume - the small velocity differences have no effect on accuracy. Either of them used for long range (>600 yd) could potentially benefit from sorting.

 

[Dave M.]

A lot of guys weight-sort brass. A lot of guys don't.

The premise, as Don suggests, is that weighing brass is a simple, quick way to figure out volume differences. A premise that many of us feel has never been proven with any consistency.

What you might do is take that light batch and actually measure the volume in, say, five cases. Then do that for the heavy batch.

If you see a correlation between weight and volume, there's your answer. And if you don't, there's your other answer.

Just buy the Lapua brass and stop wasting time sorting and have a beer or scotch by the fire pit. Much better use of your time and effort.

Dave