case volumes

5

5kl3md

Inactive
Since SAAMI has specifications for just about all cartridges, my question is this: If I weigh my 30-06 cases, will those with the same weight have the same internal volume? That would mean I could sort my hunting brass by weight and not have to worry about different manufacturers.
 
The short answer is (no), even if you had all the same headstamp as in
RP, Winchester etc. There will always be differences in the wall thickness
and the web regardless if they were all from the same batch lot.
 
Without going out and trying a few, my answer would be towards a more practical yes, based upon differences of wall and web thicknesses should produce varied weights resulting in more varied case volumes. This could depend some on the brass formula, with Federals in particular being a softer composition but thicker with less case volume. Does that make sense, not sure? But an interesting question regardless of the correct answer.
 
As an aside note...you can perform the water volume test with your case
choice's, by that, I mean plug the primer hole with an old primer and fill
the case with water, than pour the water in the powder measure pan to
weight it.
 
Good question, I shoot four types of brass winchester, Remington, Federal & ADI. The first two are thinner then the last two, my charge on the thicker brass is one grain less using the same bullet & powder. So I would say yes to your great question.
 
Case Volume

If the cases have been resized in the same die, trmimed to the same length, and WEIGH the same, how could the wall thickness not be the same? I have found that by sorting by weigh pretty much sorts by head stamp.
 
When all the cases are preped the same way the thicker brass will be heavier, as to my post Federal & ADI the weights are very close, same with Rem. & Win. brass.
 
The answer is a definite "NO".

Weighing cases tell you one thing, how much they weigh.

Brass is an alloy and as an alloy not all brass is created equal. Different alloys will have different weights of identical size.

Here is an example of case weight vs case capacity.

{Steve, unless you get permission from the owner, you cannot post copyrighted material here. Please see board policy on posting copyrighted material. The link is OK.}

Article for above photo found here.

http://www.6mmbr.com/223rem.HTML
 
The variance in brass alloy composition, creating a difference in weight versus volume, is probably the greatest consideration in arriving at a yes or no answer. So the answer probably lies somewhere in between, depending on case brand, with no being more likely most of the times, especially, of course, if cases are being mixed. If all brass alloy were created equally, the answer would more likely be on the yes side.
 
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For my rifles, I keep the brass to one head stamp. And if it's Rem or Win, I weight sort them. Only for the 223 bolt gun do I have some mixed brass. Most of the 223 brass is segregated by headstamp, but I do have a good supply of mixed mongrel brass, which isn't prepped in any way. So...the point of this is that, when I was shooting groups and testing various resizing dies with all that brass, the groups with the mixed head stamps shot a little worse. For target shooting, the accuracy diff would have been too much, but for hunting purposes it would not have mattered.

So, yes, case weight matters, but maybe not to everyone.
 
Thanks for the information. I will weigh the cases filled with water and see what I get. If the results are interesting I will post them here.
 
_I would think the thicker has less volume & would hold less water. I don't mix brands, I will load 10 Winchester & 10 Federal with the same charge to see how they group. Found that by lowering Federal ( thicker ) 1.0 gr. from 41.5 of IMR4064 to 40.5 grouped the same. That's coming from a Rem. 700 308 cal. With a Sierra 168 gr. SMK. Tried Hornady A-Max 168 different ballgame,bullet has to be seated deeper, almost a compressed load, my barrel has very little free bore.
 
cw308 said:
_I would think the thicker has less volume & would hold less water. I don't mix brands, I will load 10 Winchester & 10 Federal with the same charge to see how they group. Found that by lowering Federal ( thicker ) 1.0 gr. from 41.5 of IMR4064 to 40.5 grouped the same. That's coming from a Rem. 700 308 cal. With a Sierra 168 gr. SMK. Tried Hornady A-Max 168 different ballgame,bullet has to be seated deeper, almost a compressed load, my barrel has very little free bore.
Click to expand...

How did you determine one is "thicker" than the other?
 
Steve 4102, I thought all brass was the same, reloading Winchester & Remington brass new from Midway USA. My friend I shoot with doesn't reload saved me his Federal match cases. When I sized & trimmed them , using the same load , the powder went into the case neck. Rem.& Win. cases were at the bottom, even when trimming looking at the brass looked thicker, measured .015 on Federal .012 - .0125 on Win & Rem.
 
Weight empty, plugged case, note weight, fill with water, you want a flat meniscus, then weigh again. The difference is the case capacity, in grains of water. Don't pour the water into the pan. You weigh the case AND water.
 
cw308

You are exactly right with the Federal brass. Those cases and a few others throw a wrench into this whole weight versus volume formula. All brass is not created equally which keeps the relationship from being simpler.
 
Two things can mess you up. One, as mentioned, is the alloy difference. Cases are made with anything from 80:20 (copper:zinc) to 60:40 brass. The densities vary as follows:

From Matweb:

Copper:Zinc / Density at 68°F / Notes

60:40 / 8.39 gm/cc / (aka, Muntz Metal)

70:30 / 8.53 gm/cc / (aka, Cartridge Brass)

80:20 / 8.67 gm/cc / (aka, Low Brass)

100:0 / 8.93 gm/cc / (aka, Copper)

And if you look at the SAAMI drawing there are tolerances on rim thickness, extractor groove angle, and head diameter. Because the head is mostly solid, it doesn't contribute to interior volume when it is lighter, nor subtract from it when it is heavier. The sizing die doesn't touch it.
 
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