Water weighting cases

[Bowhunter4]

I was talking to john at 21 st century shooting about water weighting case. We where talking about how much of a pain in the but this was to do because we have to put an old primmer in the pocket and take it out. A couple of days later this whats comes in the mail. If they are not on web. site yet he has them ready to ship. $19.99 for the pair. Found this product to help stabilize the weight of the Case and to have a very tight water seal. what a cool idea... thanks
www.21stcenturyshooting.com

 

[Terry]

I like this item.

A friend taught me to do it with H380 vs water.
Gets the Job done without the mess.

 

[Bowhunter4]

anybody else have any other ideas??

 

[Jeff A]

If you are doing this for input in the QuickLOAD program, you should do it in fired cases from the gun to be used. Do not remover the primer first, but wait until you are done.

 

[jlow]

You can do this but you need to size the case and neck and do any headspace adjustments first if any of these sizing is going to be done before firing. Thre reason being it is the case volume at firing that matters. This is where the problem comes as I don't really like to do any sizing before the case is clean and I also don't like to clean the primer pocket (with SS media) once the case, neck, headspace has been adjusted.

 

[Billch]

Is there is some conflicting advice here? Is this about measuring case weight or volume?

Weight/H2o volume a fired un-sized case vs fully re-sized.



B

 

[Nvreloader]

Quick Load states to use a fired case with a rounded dome of H2o at the case mouth.

YMMV,

Tia,
Don

 

[jlow]

Is there is some conflicting advice here? Is this about measuring case weight or volume?

Weight/H2o volume a fired un-sized case vs fully re-sized.



B

What is of interest is case volume not weight. The reason is case volume affects the volume of powder your case can hold and the excess volume left when powder is added.

The most accurate way to figure out case volume is to weight the case, fill it with water and weight it again. The difference in the two weights is the weight of the water in the case which equals its volume. The density of water is such that 1 ml of water = 1 cc of volume. Because it is work intensive to do, people sometimes just weight the case and assume that more weight means more brass in the case which means less volume since some of the volume is taken up by the excess brass.

All of this is of course is only true if the outside dimensions of the case is constant i.e. the case has been full length resized – thus the rationale for using a fully re-sized case vs. an un-sized case.

 

[butchlambert]

Sounds like a bunch of people have a lot of extra time on their hands.

 

[jlow]

Now you understand why they say precision reloding is a hobby for retirees ;D

 

[butchlambert]

I'm retired, but have a lot of much more important things to do than filling cases with water.

 

[mikecr]

No, you shouldn't FL size cases to be matched by H20 capacity. They must be measured at their most consistent form & that is unsized fully fireformed.
After matching the CASE VOLUME, then you can muddle it all up with sizing & see the volume variances added.

It's unlikely you'll ever match FL sized H2O capacities

Bowhunter, any plug will do, and that shown should work well.
I stand cases on a plastic golf tee(inserted in flash hole).

 

[4xforfun]

Has anyone done any reserch on weight vs volume? I will bet that MOST of the time the heaver the case, the less the volume....and visa versa!

Anyone???

 

[markr]

Sounds like a bunch of people have a lot of extra time on their hands.

Spot on Butch!

 

[jlow]

That is interesting you say this; do you have any data to back this up?

This is because unless you fired every case with exactly the same setup (powder, annealing, primer, temperature, bullet, seating depth, case volume….etc), and you cannot because at least one of the variables is in fact case volume which you cannot control, you are not going to get the same pressure on the case and thus the same external case dimensions. It’s a myth that all fired cases expand to chamber dimensions, one only has to size a bunch of cases to know that they all don’t resize with the same effort, and for that matter their headspace can be significantly different.

I have in fact measured case volume with the water method in FL sized cases and matched them well with case weight – 223 LC09 brass, water capacity in x axis and weight in Y-axis. Correlation coefficient of 0.7.

 

[CatShooter]

Has anyone done any reserch on weight vs volume? I will bet that MOST of the time the heaver the case, the less the volume....and visa versa!

Anyone???

Yup... did it a long time ago.

I don't want to start a pissing match, so I'll pass on commenting, except to say most opinions here are wrong... and the efforts on measuring are miscalculated.

 

[jlow]

That’s because an opinion is exactly that - an opinion and unless there is data behind it, it’s nothing but vaporware.

People with data are also not in any way infallible but the difference is when a study is done, you have something solid to view, discuss, compare, and move forward on – I have always been told that data do not lie, only people lie.

Progress in any scientific field, and yes this is one, can only progress based on doing work, sharing results, and being willing to keep an open mind that your interpretation is incorrect and moving on with a corrected conclusions.

 

[jlow]

Right dmoran, we had this discussion before – as you may know, I also like your idea of the ball powder.

The way I deal with the weight variations is to not use the cases in the two extreme ends except for fouling. I also use cases of the same approximate volume in the same group. What I am not sure about and have not tested is whether using different brass volume can take you out of a node. One way I have dealt with this is to just use LaPua 308 brass which appears to be might tighter in their volume. I still weight sort but worry less….

 

[21shooter]

Hi, A small video , NO MESS Easy http://youtu.be/kR69vKiYX1E
Thanks, John
http://www.21stcenturyshooting.com/Primer_Pocket_Plugs.php

 

[jlow]

If you are using the fluid method, you will have to make sure that you get a reproducible meniscus. This technical term just means the shape of the surface of the water which can vary since water has high surface tension and will go from a concave to a convex shape.

The trouble with this is you are basically dealing with a “balloon” and you can imagine trying to blow up two balloon that small and getting them to exactly the same exact degree of convexity. This is why it is best to use isopropyl alcohol instead of water. Isopropyl alcohol or rubbing alcohol is mostly alcohol and has very low surface tension and so will give you if you are careful a completely flat meniscus.

Whatever method you use, before you do any volume measurement, the first thing you have to do is to convince yourself that your method works and you can get precise measurements. What this means is if you measure the volume of liquid you put in the same case three of more times, is it reproducible and is your variability small enough? If your variability is such that it is as much as the variability in the volume between different pieces of brass, you can see it would be a complete waste of time doing it since you will never see the data as it will be hidden in the noise of the method.