Another Basic Question - Why weigh and sort brass?

[Ackman]

There is no crap. You are wrong on the definition of anecdotal. It just means not scientifically or rigorously derived.

The problem here is that you are saying that your experience applies universally and there can be no other conclusion. All I said was that this was my experience, how it was derived, the sample size and my conclusion.

To me, anecdotals are also from outside scources, and it doesn't matter. My Oxford American dictionary is in the computer. If you insist on arguing definitions, do it with someone else.

The problem here is that you've got it backwards.
Lots of threads about weight sorting. People talk about the prepwork they do on fresh brass and show what careful/exacting reloaders they are. Sorting by weight is one of the buzzphrases. The assumption being that cases of like weight will have the same internal volume. Since new cases can vary in length, sorting virgin brass is meaningless. I wanted to find out if lighter weight meant more volume and vice versa. To do this doesn't take 1000 samples or even 100. It doesn't require bell curves or statistics or averages or anything else. I weighed about 100 each WW and IMI .223 cases, took the heaviest and lightest of each headstamp, then several in between. Fired them, trimmed to the same length, then weighed each one. Then neckturned and re-weighed....now they were all the same externally. Then measured water capacity of each one - several times - using an eye dropper and a magnifying glass to check fill level at the casemouth. For weight sorting to have validity, lighter cases need to hold more than heavier cases....no exceptions. Instead, the heaviest IMI also had the most volume and the lightest was about in the middle......internal volume difference between most and least was .2gr of water which takes up almost no space. The WW brass varied by about .7gr water internally and the heaviest case held 2nd most volume. The WW brass had considerably less weight variation from heaviest-lightest than the IMI, but more than 3X the internal variation. With both headstamps the relationship between weight and volume was all over the place, there was none. If the whole reason for weight sorting is that weight indicates internal volume......for a weight/volume assumption to be true, it has to be true with every case. Caseweight of that brass told nothing about the boiler room capacity.

There're no reloading police. People can do what they want. If weight sorting brass makes a person feel more confident, they should do it.

 

[boogershooter]

Hey Ackman, I Believe, and also appreciate what you say and have posted to save me the time of weight sorting! Thank you.

 

[BoydAllen]

Ackman,
Seriously interesting data that took time and effort to obtain, thanks for sharing it. It is fun to learn new stuff. I have never weighed brass for a much more compelling reason....laziness.

 

[memilanuk]

Ackman,

I don't doubt that for any given brand or lot, there is a possibility for individual cases to have more or less volume relative to their weight. And I fully understand that the 'weight' can be in places that have absolutely nothing to do with the volume i.e. case head, rim, etc. Where I do disagree (for what its worth) is where you seem to be looking at *individual* cases, I (and I presume Steve as well) are looking for trends. In *general* a heavier case of similar external dimensions will probably have a slightly smaller volume. So *in general*, I'd rather have my heavier cases batched together and my lighter cases batched together, instead of mixed together. As mentioned, it's a small thing, done as much for a mental safety blanket as anything. I've seen people shoot phenomenal groups and scores at distance with brass that has had very little if anything done to it beyond the normal trim/chamfer/deburr... but if I had to 'generalize' again, I think I'd say most of the better Long Range competitors that I know do some type of weight sorting. More 'anecdotal' evidence...

Anywho, for anybody who's interested, I found the paper I did for that stats class. Bear in mind the 'target' audience was my stats professor, who was not a shooter and far more interested in me demonstrating a basic level of competence of certain statistical techniques, rather than how I conducted the project. I was just glad she let me go this route rather than crunching numbers on various gov't collected data

math201-project.pdf

 

[coolt]

At the risk of starting another fight, has anyone considered variations in the density of the brass alloy itself?

 

[jo191145]

Hmmnnn

Just read this post for the first time. Came up with a half baked crazy stupid idea to solve this weighing mystery. Just might work tho.

Weigh a certain case. Cut it with a hacksaw just above the web. Mount the web in a milling machine and cut it down to "just above the web". Now weigh that web/casehead and you should have a pretty close idea of where the weight variation comes from.
Obviously you'd need to do quite a few cases to come up with some data.
Different lots and manufacturers will have different results too.
I recall a post about the possibility of some variation in the neck. Valid point. Lets say neck turned brass is better.

My current lot of Lapua 6BR probably has huge weight fluctuations just in the caseheads. The rim thicknesses alone vary by .004". Diameters are good but I had to stone down the headstamp on 20% just to fit in my shellholder.

Anyone have a clue of what I'm thinking? ;D

Don't look at me. Metal work is not my forte.

Sorted all my brass in an accurate 204R once. Tried some groups with the lightest and heaviest cases. Saw no difference. Dare I say it the mixed light and heavy weights actually grouped a little better. Dumped em all back together and haven't thought of it since.
That does'nt mean a different lot of brass might not benefit from weighing tho.

 

[Ackman]

My current lot of Lapua 6BR probably has huge weight fluctuations just in the caseheads. The rim thicknesses alone vary by .004". Diameters are good but I had to stone down the headstamp on 20% just to fit in my shellholder.

Anyone have a clue of what I'm thinking? ;D

Yes. Loading a big bunch of .223 there'll always be cases that fit the shellholder more snugly than others, and a few are tight. A couple don't go in at all and get tossed the first time. There's casehead thickness, diameter, and an extractor groove that can all vary. And it's all caseweight.

 

[Beau]

I have tried controling the meniscus by adding 25% alchohol to the water and adjusting for the change in density.

Right thought, wrong way. The meniscus should be pretty darn uniform. In chemistry and biology, we were told the meniscus was uniform in any given measuring device. What you want is a wetting agent (i.e. soap or a detergent) to lessen the surface tension. But not because of the meniscus, but to eliminate bubbles from the inside surfaces of the case. If you want to get real precise, fill the cases with a hypodermic needle until the meniscus collapses and leave it where it settles.

 

[TonyR]

Beau. That is very interesting. I will look into the case and see if there are any bubbles. The issue I was trying to address is the tendency to make a sort of dome above the rim before it overflows. I have found it hard to keep the fill constant. Good idea about the bubbles.
Thanks

 

[holstil]

Not that I care to start weighing cases, don't have time, barely have time to shoot. I am interested in this though.
What about submerging the cases in what ever solution deemed best, then while under, place cellophane over the top. Pull out, let dry, remove cellophane, drain onto scale.
Not sure of the best way to remove the flexible lid. Maybe just let it all together and subtract before to after.
Probably best to insert a primer upside down. You wouldn't want variances in filling the primers. Better yet, you probably need a machined plug to fill the pocket.
Time for sleep, Jim