308 Win Case Volume Differences

Andy

Andy

CGN Ultra frequent flyer
Rating - 100%
329   0   0
Location
Ottawa
I had 10 different brands of 308 Win (and 7.62x51) cases on hand, and thought I should compare their internal volume differences so that I could adjust loads accordingly. I resized them in an RCBS Small Base F/L sizer, reprimed them with a dead primer and then weighed them. I then filled them with water to the top of the neck and weighed them again to compare their relative internal capacities. You'd expect that the heavier the case, the less the internal capacity and vice-versa, but there are some exceptions.

Weights are within about +/- 0.5 grs. Please understand that I only weighed one example of each - using the average of 10 of each example would have been more accurate, but I think that this sampling is fairly indicative of relative weights. In other words: "Your results could vary".

Brand - Weight - Volume (of H2O)

Hornady Match - 159 grs - 58 grs
Dominion - 160 grs - 58 grs
Federal - 162 grs - 57 grs
Winchester - 168 grs - 56 grs
Hirtenberger - 168 grs - 58 grs
Norma - 170 grs - 57 grs
Remington - 170 grs - 56 grs
Lapua - 177 grs - 55 grs
IVI - 187 grs - 55 grs
DA - 196 grs - 53 grs


Handloader 257 had an interesting article on the 308, and within it they conducted a "Brass Endurance Test". It probably drew some hate mail, because the results might not have been what was expected, and people are very sensitive about their favourite brass. We think that thickest and heaviest (usually military) will last longest, but that was not the case. For example (fudged a bit to keep it simple):

1 - Norma (24) reloads with F/L resizing
2 - Federal (21)
3 - Lapua (15)
4 - Winchester (14)
5 - Federal (13)
6 - Hornady (12)
7 - Federal Military (11)
8 - Nosler (10)

The Norma actually was relatively thin ahead of the web where most case separations occur, and the Federal Military faired near the bottom. I think that heavy military brass might be strongest as far as the extractor groove area goes, but they might not go as far on multiple reloads (which was never intended).
 
Last edited:
The findings are indeed interesting, and I for one would have rated Winchester well ahead of Federal, in terms of longevity, and have always held that Winchester brass is pretty uniform due to it's light weight compared to some others. Not all manufacturers use the same alloy, so it would not necessarily follow that weight alone is indicitive of volume.

Andy, after FL resizing, did you trim all the cases to an equal length? I wonder if it is possible that case "A" had greater volume than case "B" despite it's greater weight, due to a longer neck?
 
Boomer said:
Andy, after FL resizing, did you trim all the cases to an equal length? I wonder if it is possible that case "A" had greater volume than case "B" despite it's greater weight, due to a longer neck?
Click to expand...
No, but any difference would be miniscule (we're talking at most +/- 20 thou of a narrow neck compared to over 2000 thou for the full case), and well within the +/- 0.5 grs that I included as margin of error. Probably less too than the variation you might find within a given brand.
 
Here is some more info on the test
The rifle: Sako TRG-22

The powder: 45 grains of Varget

The bullet: Berger 168 gr. match

Case failure defined as anything from incipient to complete head separation.
Click to expand...

With Federal GMM brass I found that after 3-4 firings spent primers would be falling out in my tumbler.
I have since moved to Lapua.
 
Boomer said:
The findings are indeed interesting, and I for one would have rated Winchester well ahead of Federal, in terms of longevity, and have always held that Winchester brass is pretty uniform due to it's light weight compared to some others. Not all manufacturers use the same alloy, so it would not necessarily follow that weight alone is indicitive of volume.
Click to expand...

Fed has a nasty habit of changing their alloys from run to run. Some Fed GM brass will only take a few strong reloads before the primer pockets fall out.

I was lucky enough to get some Fed GM component brass years ago that was built like a tank. I doubt even Lapua could have taken the beating I gave this lot of brass.

Sadly....all gone.

Win seems to be the most consistent as far as durability goes. At least over the 6yrs I have been shooting it.

Recent lots are supposed to have a larger case volume. Apparently PALMA shooters are on the prowl for this stuff and my stock lasted but a few minutes when the word got out. Sadly, now on backorder yet again.

Andy, thanks for confirming what I have said for a long time - case weight is not indicative of case volume.

Jerry
 
It's best to work up loads for each brand individually, but f I'm being lazy or have runs of mixed brass to load, I work up a .308 load in Federal brass and then don't worry if I use the same load in Remington or Winchester brass.
 
You must log in or register to reply here.
Back
Top Bottom