Most accurate way to measure case volume

Frog4aday said:
Yes, that's how I understand it (the alcohol helps with the 'mounding' of the water...but I didn't know how to say it or explain it.)
Click to expand...

They call that a "meniscus" and it's caused by surface tension. I had never heard of the alcohol trick before - it must do something to alter the surface tension and change the behavior of the water. That's a neat trick. Thanks.
 
Most of the time when I looking for case volume differences, for comparing case capacity of my established loads when trying new brass. I simply compare the total volume of my particular powder used for my load in duplicate(to check for packing consistency), and compare the net powder weight between the two cases. I use a spent primer to plug the flash hole. It's not as scientific as determining standard water capacity, but more then sufficient to understand load volume adjustments. Recently used this approach to determine a 2.5-2.7gr increased weight capacity of Retumbo in Norma 300WM cases compared to Winchester cases. Took less then 5 minutes with no fuss. IMO.
 
I pop the primer out weigh the case and a bullet, fill the case to the top with water, seat the bullet to the coal I want, the excess water leaves through the flash hole but the rest stays in there then I weight it again, my 26 wssm with a 139 scenar has a 54 grain water volume where it is 50 grains with the 156 in it
 
You don't use ALL alcohol. You add a few drops to the water. This helps flatten the meniscus, making it more uniform and easy to get an accurate measurement.

I agree - don't use any other liquid besides water for the measurement. That wasn't what was being suggested. A few drops of alcohol is all. Won't 'hurt' or affect the measurement in a negative way.
 
TwoMore said:
I pop the primer out weigh the case and a bullet, fill the case to the top with water, seat the bullet to the coal I want, the excess water leaves through the flash hole but the rest stays in there then I weight it again, my 26 wssm with a 139 scenar has a 54 grain water volume where it is 50 grains with the 156 in it
Click to expand...
I'm reading this and "not getting it". Are you seating a bullet in a case filled with water...and no primer in the case? Is that not squirting water all over your press and surrounding area? Then, when you are done, how does the rest of the water not leak out the primer hole?
 
Frog4aday said:
I'm reading this and "not getting it". Are you seating a bullet in a case filled with water...and no primer in the case? Is that not squirting water all over your press and surrounding area? Then, when you are done, how does the rest of the water not leak out the primer hole?
Click to expand...

When you were a little kid, did you ever put your thumb over the end of a drinking straw and then pull it out of your drink ? The juice stays in the straw, because you've got a vacuum there. Air can't get in at the top, so the juice doesn't pour out at the bottom. I think that with a bullet plugging the whole in the neck of the cartridge, the water would stay inside the cartridge case. The only water you should see would be what had formerly been in the neck of the cartridge case, and that was pushed out by the bullet during the seating process. This amount is minima, and I wouldn't expect to see a big mess. I've never done this, but I'll bet that it works just like Frog4aday described the process.
 
nicholasjohn said:
When you were a little kid, did you ever put your thumb over the end of a drinking straw and then pull it out of your drink ? The juice stays in the straw, because you've got a vacuum there. Air can't get in at the top, so the juice doesn't pour out at the bottom. I think that with a bullet plugging the whole in the neck of the cartridge, the water would stay inside the cartridge case. The only water you should see would be what had formerly been in the neck of the cartridge case, and that was pushed out by the bullet during the seating process. This amount is minima, and I wouldn't expect to see a big mess. I've never done this, but I'll bet that it works just like Frog4aday described the process.
Click to expand...
You got it :) Works perfect no mess at all just a few drops to wipe up with a paper towel. hydro forming makes more of a mess;)
 
Add about 10% alcohol to the water. It'll help with air bubbles. I prefer twice fired brass so it's fully expanded to your chamber. Fill it to a slight bulge with a large syringe ( mine holds about 3 oz's) , and while holding it... touch the bubble lightly with your finger tip (s) to remove the water so it's flat. It's easy once you get used to touching the bubble removing the fluid to make it flat with the case opening. This way doesn't get water on the outside of the case as easy to skew your results.
 
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