223 testing results

[Metal god]

308 brass is 170 to 190 grains . All my LC brass is in 180 to 185 area . I have some Remington thats in the the low 170’s and heard of old Win brass being as light as the 150’s .

I said I was going to have to look at my data . Haven’t yet and out of town now . “If” I remember when I get back I’ll post the case weight to volume data I have .

[tangolima]

Metal. It would be wonderful if you can post your data. I have updated my equations to include the external dimension error. But I need real measurement data points.

Just picked up 50 or so Norma .223 brass. They seemed to be from the same batch. Did a weight sort. They are absolutely the best I have seen, even better than RWS. All 50 pieces neatly sit between 91.5 - 93.3gr. Amazing!

-TL

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[Unclenick]

Here's data from a brief weighing of Lapua brass. The histogram quite clearly reveals two sets of tooling were involved. If I had doubled the sample size, you would have seen the bell curve shapes of each tool's product's weight distribution much more clearly.



The Winchester .308 cases made for the 1992 Palma Match, which the U.S. hosted, weighed a scant 150 grains, IIRC, having been redesigned for maximum powder capacity, which was accomplished in part by going to the semi-balloon head design, which they seem to have migrated to other cases (it saves brass cost). In 2001-2005 somewhere, I bought 500 pieces of Winchester new brass on Commercial Row at Camp Perry and weighed them all. The distribution is in the illustration below. You can see four distinct tooling sets were involved, each making its own bell curve peak. The tails overlap, making it impossible to sort by tooling exactly. I note that a few more recently purchased Winchester cases were in the 162-166 grain weight range, probably reflecting changes after the 2007 shift of centerfire ammunition manufacturing from East Alton, IL, to Oxford, MS.

[akinswi]

Nick,

Is there any correlation to brass weight vs volume?

When I went to shooting 1 manufacturers brass on a lot to lot basis, I did get better scores, I dont shoot many groups anymore Just scores

I found weighing brass and bullets got to be too tedious for my liking. But the graph is very interesting .

[Unclenick]

All that Winchester brass came in the same bag, yet clearly was off four different machines. One time I measured a number of 308 cases by weight, then I divided the weight difference by the density of 70:30 brass to get a change in water weight for the same volume change, then did actual water capacity measurements of them, and I found the water capacity change was predicted by the weight difference to an accuracy of ±20%. So some of the weight difference (this was mixed brass) was due to head tolerances down below the bottom of the powder space. I have been trying to find what I did with the original record of that, but may have to repeat it. Also, this kind of thing can change over time as manufacturers contract out to each other or tooling changes.

[std7mag]

While interesting data, (Thank You for the time & effort spent to the OP!!), unless your shooting an AR with bulk FMJ it really means little.
At least to me.

Had you been testing with a free recoiling benchrest rifle using match bullets (along with a trigger set in ounces, not pounds) and slow fired.
That might have proven whatever concept you were looking to achieve.