Case weighing or internal volume - which is more important?

[geordiesniper]

Hi All.
What I am trying to find out is which of the following actions has more impact on long range accuracy.
Weighing cases after neck turning and batching them within 1/2 a grain or less, or measuring the case internal volume. If it is internal volume what is the best medium to use? Or would neither method have any real world improvement to reloading consistency over the other?
Thanks.
PS. I sort my bullets out into 0.1 grain lots. Weigh my powder on an Acculab scale to +/- 0.02 grain accuracy (assuming the scales are correct), point my bullets etc.

 

[4xforfun]

I simply weigh mine and either ...

Scribe a number on them from 1- whatever, depending on how many I weigh....I shoot them in order.

If I do 200 or more, I seperate into batches of 50...ie, the lightest 50, the next lightest 50, ect.

Now, there are guys who say that weight sorting is meaningless...it has no corolation to actual volume. Some of these guys are top notch shooters. I can't / won't argue with them.

I just can't figure out that given a batch of cases made from the same batch of alloy(same density)....fireformed to exactly the same O/D and exterior measurements, trimed to the same length, ...ect....if one weighs more than the other, where is the weight comming from. More material. If the outside measurments are the same , where is that extra brass. It has to be inside the case.

The nay/sayers say not.

I guess I am just not smart enough to wrap my peon brain around it all!! ;D

 

[geordiesniper]

Thanks. I think there was an article on this somewhere that also stated that weight sorting has no correlation to internal volume, because the variation is caused by more/less material in the case web.
But who am I to argue that one! But there could be some value in that statement, but I guess I will just join the 'peon' gang and weigh the brass and 'batch' it, because it makes me feel good.
I know that in the real world it is the wind speed that will determine where my bullet goes and if I got God to reload for me, it would not make a difference in my shooting.

 

[Nomad47]

I've never bothered, but it should be fairly easy to determine if case weight is related to case volume.
I suggest firing 5 identically loaded rounds, then trim all 5 to identical lengths. Then weight sort lightest to heaviest and then see if case capacity (H20) is in the reverse order.
I am interested in your findings but I'm not interested in performing the test.

 

[Shynloco]

To me, case capacity is not something I even worry about or consider when I'm going after accuracy. I do weigh my brass (all Lapua) when first prepped and again when the round is fully loaded and then put them in weight order from low to high. Now with my 6mmbr, I allow for no more than 1 gr spread between that low and high because thats where I have found I maintain the best consistency in shot groups. But the entire business of "case capacity" strikes me as having way too many variable potentials some of which there is nothing I can do about.

 

[geordiesniper]

To me, case capacity is not something I even worry about or consider when I'm going after accuracy. I do weigh my brass (all Lapua) when first prepped and again when the round is fully loaded and then put them in weight order from low to high. Now with my 6mmbr, I allow for no more than 1 gr spread between that low and high because thats where I have found I maintain the best consistency in shot groups. But the entire business of "case capacity" strikes me as having way too many variable potentials some of which there is nothing I can do about.

Hi Shynloco, I keep my current brass (about to be replaced) in half grain spread per box of 50 and also use Lapua. I agree that there are so many variables in trying to achieve the ultimate accuracy that we get wrapped up in the detail and try to resolve all the many variables, of which some will have a definate impact on accuracy whilst others less so. Regarding brass weights/internal volume I think that I will just keep it simple and stick to case weighing.
Thanks, Les

 

[Leaddog]

I believe that case capacity is a more valid measurement. Weighing cases only will vary due to the weight of the case head, thereby skewing your results.

Using at least 91% alcohol, weigh your once fired case with primer still in case, fill to case mouth, and weigh again. Subtract the difference and you will have your capacity. Alcohol is easier to work with and more accurate as water has air in it.

 

[geordiesniper]

I believe that case capacity is a more valid measurement. Weighing cases only will vary due to the weight of the case head, thereby skewing your results.

Using at least 91% alcohol, weigh your once fired case with primer still in case, fill to case mouth, and weigh again. Subtract the difference and you will have your capacity. Alcohol is easier to work with and more accurate as water has air in it.

Hi Charlie, never thought of using alcohol and when I have seen videos of people using water, it never seems to be level with the case mouth, but has a large 'blob' outside the mouth.
NOTE TO SELF:- DO NOT DRINK THE ALCOHOL !!!! DRINK BEER INSTEAD !!!
Thanks, Les

 

[lloydx2]

Is it not more about occupying volume in the chamber? No matter where the extra material is displaced it still occupies volume in the chamber. Less chamber volume less room for powder gas to expand, more pressure? I have heard one argue that density plays a role. From what I understand most brands of brass is pretty even. 25-30% zinc. Case hardness can be differnet from different makers but that doesn't effect weight.