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Discussion in 'Long Range Hunting & Shooting' started by CWM-RHG, Jul 20, 2019.
Looking for input on how to precisely measure case volume. Any Ideas????
Get a once fired case with the spent primer still in it. Weigh it. Add water to top of case mouth, weigh it. The difference is your case volume. Some folks, to be even more precise, pop the primer and insert it in backwards and do the same thing. Some add a touch of alcohol to the water to improve flow or...something. Hope that helps.
I have tried that but the water sometimes humps up on the top of the case and sometimes doesn't .. Maybe the alcohol will help it flow Thank you....
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.)
Take the time to wipe off the bubble on top and make sure it's not concave for consistency.
If you add isopropyl alcohol to water, the miniscus is reduced, but not eliminated.
When measuring CC's in engine building, we use blue kerosene, this is also what I use to measure cartridge volume, no miniscus forms with kerosene.
I measure with a Burrette that is graduated in 10ths of a CC.
Using a liquid like kerosene or even water seems a bit messy. I could see how the kerosene could be better than water but seems like it could even be messier. I haven't tried it but I would think using a spherical powder could work pretty well. Use one of the long tube funnels like the Forester brand so it compacts and fills the case fully? Just a thought. Has anyone out there tried using a powder to measure volume?
The problem with using alcohol or kerosene or ball powder is that they do not weigh the same as water.
Water weighs one gram per centimeter... and that is THE standard, and if you are using case volume in hand loading loading software like quick load, the volume MUST be in water weight.
The bump of water at the mouth of the case (caused by surface tension) is easily removed with a piece of paper towel.
I prefer to have a convex meniscus which is easily obtained by filling the case and making sure to not allow any cloth to touch the meniscus when wiping any water from the outside of the case. Concave or convex typically will change the reading around .2 of a grain.
I'm glad somebody else mentioned this besides me. No mess at all. I just wanted to know which case had more volume and what the case weight difference was between Rem. Nosler. Norma and Federal. I used Win. 748 powder. Tapped until settled and scraped case mouth level. No water mess. It was with 300 Rum cases. I posted results. Nobody replied . I thought well, that must off been a stupid thing to post ! Lol. I'm sure it's been done forever.
Get a cup of water, put one drop of dishwashing soap in and gently mix. This will take care of any "humping".
Using detergent (or alcohol) in the water is probably best if you must have water weight. If you're just comparing one brand to another for your own information, use a fine grain ball powder such as AA#2 and at least 5 cases of each brand you want to compare. I use a drop tube when using this method. Weigh the cases before hand to make sure they are all as close to uniform as possible. If there's a large variation in the case weights, you might test these against each other as well. Just make sure you use the same powder each time.
For my purposes since I don't use software would be to get a general idea of how close my brass was in volume. Someone I respect recently made a statement that his Norma brass though off by a couple grains or so per batch all had very close to the same case internal volume. I think I would have a chance of proving that or disproving using the small spherical powder like hunter. Some handgun powders I don't think would work well at all as they are too fluffy. But I believe the ranshot hunter would work great and you could probably resuse the 100 grains or so it might take after you were done. Its very small and fine but still very heavy for it's size and flows almost like water. But I'm sure it would not be useful in a software app. I think magpro also has a similar consistency.