Weighing brass?

coyote_220

New member
When you are wieghing cases how much difference is there if the cases you are using only have 1 or 2/10ths of a grain weight difference? Is it really that important to weigh your brass and use the same weights I mean how much does that really affect accuracy?

Thanks
Shawn
 
I don't think you will ever notice even a 2 gr difference. If shooting real good equipment at 1000yd target, under ideal conditions, you might be able to see a slight effect, but I doubt it.

I sometimes weigh cases, but more as an indication of overall brass quality control, than because small weight differences are important.

Case wall thickness run-out is much more important.
 
Let me run this by you guys. I have been doing it for years, but seldom see referance to it, anywhere on the 'net.

First, you need a piece of drill rod just a little longer than the overall length of the case in question. One end flat and the other turned to a point on a lathe. Next, you deburr the flash hole.

It doesn't matter which case you select as your baseline. Just measure it and re-zero your dial caliper. This case will be zero. It might, in fact be 2.355" but it doesn't matter, I just change the dial to indicate zero. I made up a board with divisions the whole length, in thousanths, plus and minus, from the center. This board is about five feet long. Now, I measure every case. if it is .005" under, it goes in that (-.005) column. A case that might be .003" over would go to the (+) other side of zero. What I'm measuring is the web thickness, and it gives an indication of internal volume, since this portion of the case shows substantial variation, much more than a thou difference in neck thickness.

Anyway, when I'm finished, and done with all the rest of the culling and separating, I divide my cases thus:

I save the ten thickest and ten thinnest for load development. Then I scratch a mark on the base, to the right or left or exactly in the middle of the headstamp. Generally, for instance, I wind up with 40 low and 40 high, and 100 right in the middle. Equal thirds would probably be about the same? Anyway, it seems that I get more consistant velocities, all things being equal. I dump them all into the tumbler, and they all get the same load, but I put them in separate boxes. Accuracy is a tossup, but the velocity does show a slight difference, not sure if it would be significant for everybody.

Jack and Dave, both of you guys have been around. Have you tried this, have you heard of it, and what might be your unvarnished opinion? You know, as in gambling; everybody has a system that doesn't work! I can take it. lol
 
Never heard of that sorting system before Leonard. You probably are just sorting by weight, only not as accurately as by weighing. Weight counts in the sense that it is a(one of many) factor defining the combustion volume. It does matter and can be measured. A given amount of powder burnt in a smaller volume will develop higher pressure. More case weight=less volume inside. Less volume=higher pressure. Higher pressure=more velocity. Within the range of volume areas we have from small case weight variations, the differences are barely measurable, and will only show up at very long range, where less than 99.9% could hit the target.

These small velocity differences only show up at looooong ranges. Case wall thickness run-out opens groups in all directions at all ranges.
 
Thanks for the info all I appreciate it much. I had no clue to check case walls. How would one measure that? Is thicker better or thiner better? Sory if this seems foolish but I am new to reloading.

Thanks
Shawn
 
Coyote_220
What matters about the case wall thickness is that it is the same all the way around the case. In other words, not thicker on one side and thinner on the other.

The best way to measure it is with a NECO gauge because you can measure near the head. The other way is to just measure the thickness at the neck. This can be done with a multi anvil micrometer or something similar.

My source for the better reloading tools is: Sinclair International.
http://www.sinclairintl.com

Be forewarned; Sinclair has lots of neat goodies. You will see things there you will have to have.
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Thanks for the link Jack! I don't think there is a web page on the internet thats hunting related that I couldn't find something I just had to have
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Thanks
Shawn
 
Leonard, that IS a new technique on me!

Obviously going to give you an almost instant measurement of relative internal capacity - as you are intending.

I can only speculate on the effectiveness. You have been "doing it" and so have a much better notion of it than I. But, my speculation would be the same as weighing - small differences (a couple thousandths by your method, as opposed to a couple grains by weight), will never show up on the target. Larger differences, in good equipment, at long range, yes they will show up.

This technique is obviously working for you, so I wouldn't change it.

- DAA
 
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