another test that worked out

[marksman]

so I have been sorting cases by weighing them for years and because I use quickload to find my max load for the individual rifle I weigh the internal volume using water, its something Nick Harvey wrote about years ago when asked about weighing cases, smart bloke
anyway I thought I would put up the weights of the cases and with water that was not looking very good for a test looking for uniform volume at first for those who do weigh there cases to show variances and that the water volume test is the go if you have that much spare time

308 lapua cases

case weight, filled with H2O, H2O weight
177.6gr , 234.5gr, 56.9gr
177.5gr , 234.3gr, 56.6gr
176.3gr , 232.8gr, 56.5gr
175.8gr , 232.2gr, 56.4gr
177.5gr , 234gr, 56.5gr

as you can see some of the weights of the cases are all over the place as is the filled with H2O figures
but the volume weight (H2O weight) is within .5gr and is very acceptable for fairly even pressures
before I started weighing volume I would have culled some of these cases and not used them thinking the volume weight would be unacceptable because of the varying differences in case weight
this test shows how wrong some tests can be although they do sound like they would logically work
so why would you sort your cases out like this, to try and get a lower ES for more uniform groups
its not for everyone

now this is OCD what do you recon Rod_outbak

[Rod_outbak]

I started weighing my completed loaded rounds about 2 years ago; had an incident where some 150gn pills of the same caliber/type got mixed in with 120gn pills.
So as a final safety check, I weigh each cartridge on a little set of jewellers scales, and tally the weights.
Over time, it has also given me data to use as benchmarks for particular brands of brass.

Now, while it's a simple and useful double-check, I was sitting there the other day, and when a (Hunting) cartridge came up as being a whole 2 grains heavier than any of the other cartridges(still less than 0.5% variance from average weight), the OCD in me was screaming that I really should pull it apart and re-do it.
Until that cartridge, I'd only been seeing a max 1 grain variance each side of the mode weight.

So, I'm hearing you.

[marksman]

hey Rod I cannot beat that
you have it bad mate

[Stix]

Im definitely going to give that a go Marksman...ive been wanting to do it since (was it your dasher thread?) you last mentioned it...

But im going through a resizing & cleaning regime with 3 cartridges first, (got some 204's & 7-08's in the tumbler that im drying off as soon as i write this).
Then im going to get this annealing bizo happening & sorted so i know ive done what i can with neck tension (i picked up my tempilaq paint on Friday).

Then ill resize necks & shoot off...

Then ill do the volume test...

Its just all time...time...time...

[Sergeant Hartman]

Lol I just got a needle point blue gas bottle and car wash and wax for my ultrasonic cleaner. But no templaq paint yet

[straightshooter]

so I have been sorting cases by weighing them for years and because I use quickload to find my max load for the individual rifle I weigh the internal volume using water, its something Nick Harvey wrote about years ago when asked about weighing cases, smart bloke
anyway I thought I would put up the weights of the cases and with water that was not looking very good for a test looking for uniform volume at first for those who do weigh there cases to show variances and that the water volume test is the go if you have that much spare time

308 lapua cases

case weight, filled with H2O, H2O weight
177.6gr , 234.5gr, 56.9gr
177.5gr , 234.3gr, 56.6gr
176.3gr , 232.8gr, 56.5gr
175.8gr , 232.2gr, 56.4gr
177.5gr , 234gr, 56.5gr

as you can see some of the weights of the cases are all over the place as is the filled with H2O figures
but the volume weight (H2O weight) is within .5gr and is very acceptable for fairly even pressures
before I started weighing volume I would have culled some of these cases and not used them thinking the volume weight would be unacceptable because of the varying differences in case weight
this test shows how wrong some tests can be although they do sound like they would logically work
so why would you sort your cases out like this, to try and get a lower ES for more uniform groups
its not for everyone

now this is OCD what do you recon Rod_outbak

If brass cases have the same weight AND the brass in the case has the same uniformity of alloy and of hardness AND they are fired to the same uniform pressure in the same chamber THEN the effective volumes must be the same
Note that I have put the above in the form of a logical expression.
You can safely assume that brass from the same batch will have uniform alloy composition and hardness.
A variation in any factor will of course result in a variation in volume.

The test results indicated above take no account of your ability to uniformly measure accurately the weight of water in a case.
Consider these problems
Have you filled each case to a uniform level?
What is the weight of water left wetting the outside of the case?
What is the variation in water weight due to firing residue inside the case?
What is the variation in water weight due to the air pocket in the fired primer and flash hole inside the case?

So what I am trying to say is: clean deprimed cases with identical dry weights should have identical internal volumes on firing.

In my opinion nearly all gun scribblers can be safely ignored when they are dealing in anything other than basic facts.
One still popular gun scribbler in particular lost credibility with me way back in the 70's when an article in one issue of Outdoors Annual was directly contradicted by another article in a later Outdoors Annual.

[marksman]

I was actually thinking while doing this test that even though from the same batch bought they could have been from the manufacturers different batches?
I was starting to get a bit annoyed but I know from doing this test many times that the figures you need to look at are the last figures, the water volume
I have taken into account the problems you mention to consider, that is why I have a fudge factor to work within because there will never be exact uniformity,
I wish there was
my OCD gets me to check 5 cases of the same batch then add the 5 water volume figures together and divide them by 5 that gave me a H2O volume of 56.6gr
but I need this information to accurately use quickload anyway so I can work out my max load
because of the fudge factor Rod gets the trophy for OCD, although I have heard of weighing made up rounds before as a good indication for uniformity
I'm sure I read it in the "secrets of the Houston warehouse" I cant remember
http://precisionrifleblog.com/2013/10/1 ... -accuracy/
the thing is doing this test makes me feel like I have done something to help with better precision and I have found that used with some of my other OCD routine habits I can make an accurate round, quickly, sometimes within 18 shots that have never been bettered with that recipe and on more than one occasion
they said the same thing about Nick Harvey loosing credibility because of differing articles wrote years apart that contradicted, what his response was that his ideas changed as he learnt more, I can understand that myself as it has happened with me, you can have your beliefs of many years shot down in one afternoon by seeing something differently

Stix and Ziad beware there may be no turning back

[Chronos]

I agree with Straightshooter in that if cases are fired in the same chamber and then trimmed to the same length then all external dimensions should be near identical. In that case any variation is case mass can be attributed to a variation is brass thickness and therefor case volume.

I simply uniform fired unsized brass and weight them, any that vary dramatically from the mean mass may get marked and put aside for use as barrel warmers or drilled and tapped for use as a COAL case gauge.

WIth projectiles I simply sort and batch them in order of lightest to heaviest and used in that order

Chroos

[marksman]

I should have said these cases that I tested have been fired in the chamber of the rifle they are being reloaded for they are also neck turned, trimmed to minimum length, primer pockets and flash holes uniformed, VLD inside neck chamfered, using K&M, wilson and sinclair tools
the test does show weight sorting brass cases may not be the best way to test volume although it does sound feasible the way you have explained it
it is not going to be the only exercise in the world that sounds good but does not really work that well
if it was that simple winchester cases would look as good as geco and we all know some brands are made from several different sources
you should try it and see how it goes you might be surprised or maybe you can control your OCD

[Stix]

Im already gone marksman...but thanks for the warning anyway