Best way To Measure Case Volume

[HPMike800]

The thread on 'Shocking Results' brought up something I've been wrestling with.

What is the most reliable way to measure case volume? Water can't be it as I can measure the case and get different readings each time. Especially with used cases.

I have some LC 'LR' and 'Match' cases I would like to use for my Palma rifle.

Any great ideas? Ball/Flake powder maybe?

 

[BigJim]

Mike

The only measurements I have ever hear of for case volume was with water. I haven't tried this but any fine grained powder should do the job as well, talcum, mica or any small gain ball powder should give you the internal volume of the case. A gain is a grain is a grain. Your different measurements might be due to the brass stretching since you indicated that it was with fired brass.

I would suggest that you use the powder that you are going to use and fill the case up to the shoulder. Then weigh the powder, and that will be the max volume in grains for the cases you are going to use. This does not mean that you should load to the max volume for the case. PLEASE follow your reloading manual on max charge.

 

[CoverDog]

I can't think of anything better then water. Since it can't be compressed it has to give consistant measurements.

 

[HPMike800]

Thanks, I agree that a no residue liquid is the material of choice, but it seems to leave an inconsistent amount of residue in the cases when dumping it out. Perhaps some detergent as was suggested in the shocking results thread.

Don't forget, water is incompressible with respect to pressure not to temperature. It's density changes with quite abit with temperature.

 

[Cheechako]

Mike

Don't forget, the water capacity of a particular case is only used as a method to compare with other cases - if done correctly,filling the case to the top). It has no meaning as far as powder charges are concerned except as a starting point in most interior ballistics calculations.

If you are careful to wipe off any excess that may happen to be clinging to the outside of the case you should get fairly consistent results. You say that it leaves 'an inconsistent amount of residue in the cases when dumping it out' but I fail to see the significance of that.

I think you may be attaching some importance to the weight of the water that isn't there. Use the information for what it is - a comparison - and you'll appreciate it's simplicity.

JMHO

Ray

 

[HPMike800]

Ray - I'm just checking relative capacity variations of a batch of military brass for long range shooting. The info has nothing to do with load development just batching / cull out.

Gun - I was dumping the water out of the case into the tray. Dumb! Weigh the brass and then the water and the full case. Easy.

Thanks

 

[stiles]

Mike

Don't forget, the water capacity of a particular case is only used as a method to compare with other cases - if done correctly,filling the case to the top). It has no meaning as far as powder charges are concerned except as a starting point in most interior ballistics calculations.

But that's not how you measure case capacity for a given bullet at a given seating depth. Take a fired case and clean it up if you will but don't resize it and don't deprime it and discard any case that had any dents in it. Trimming and deburing the case can be a good idea. Weigh the case and record the number. Now you need to scribe a line of your bullet of choice so the scribe line meets up with the neck at the proper seating depth. Ok now fill the case up with distilled water and guide the bullet down the neck to displace the water until you get to the scribe mark on the bullet and then remove the bullet. Wipe off any water on the outside of the case and weigh the case again. Subtract the second number from the first and there you have your displacement in grains of water. That's the classic way to do it.

The way I do it these days is I take the case and neck size and deprime and then seat my bullet to the OAL I want. Then I put the case with the bullet in a piece of derlin I drilled out to holed the case head up on my digital scale and then zero out the scale. Then I fill up the case with water with a syringe till the water backs up into the primer pocket and then use a bit of tissue paper to wick out the water from the primer pocket and then take the measurement.

 

[BigJim]

Ok, I may sound dumb, but what is the purpose of doing this?

If you are going to use a powder in a table with a certain head, you already have the min and max load and OAL for that powder. Outside of measuring with a case length gage for OAL to lands, what difference will the volume of the case be unless you are not following the instructions,recommendation) of the bullet or powder manufacture???

Are there that many of you out there that have a death wish. Unless you have a pressure gage and barrel,CUP), your playing with disaster. I can't afford to replace my guns if I blow them up!!!

Jim

 

[memilanuk]

Ok, I may sound dumb, but what is the purpose of doing this?

Attempting to sort by volume for consistency, which has exactly *zip* to do with the published min/max loads.

 

[Cheechako]

BigJim

No offense intended, but you strike me as a reloader rather than a Handloader. There's a big difference. If you really think that Handloaders have a 'death wish' and are 'playing with disaster' you should stick with reloading manuals.

JMHO

Ray

 

[Ackman]

But that's not how you measure case capacity for a given bullet at a given seating depth. Take a fired case and clean it up if you will but don't resize it and don't deprime it and discard any case that had any dents in it. Trimming and deburing the case can be a good idea. Weigh the case and record the number. Now you need to scribe a line of your bullet of choice so the scribe line meets up with the neck at the proper seating depth. Ok now fill the case up with distilled water and guide the bullet down the neck to displace the water until you get to the scribe mark on the bullet and then remove the bullet. Wipe off any water on the outside of the case and weigh the case again. Subtract the second number from the first and there you have your displacement in grains of water. That's the classic way to do it.

The way I do it these days is I take the case and neck size and deprime and then seat my bullet to the OAL I want. Then I put the case with the bullet in a piece of derlin I drilled out to holed the case head up on my digital scale and then zero out the scale. Then I fill up the case with water with a syringe till the water backs up into the primer pocket and then use a bit of tissue paper to wick out the water from the primer pocket and then take the measurement.

Why???? What can you possibly have gained by going through all this?

 

[Ackman]

Ok, I may sound dumb, but what is the purpose of doing this?

If you are going to use a powder in a table with a certain head, you already have the min and max load and OAL for that powder. Outside of measuring with a case length gage for OAL to lands, what difference will the volume of the case be unless you are not following the instructions,recommendation) of the bullet or powder manufacture???

Are there that many of you out there that have a death wish. Unless you have a pressure gage and barrel,CUP), your playing with disaster. I can't afford to replace my guns if I blow them up!!!

Jim

To put it kindly......you sound unclear on the concept.

About the 'death wish' stuff.....yes, that makes you sound dumb.

 

[Ackman]

Some of the posts on this thread are kind of strange. Measuring volume is just a way to compare the size of different cases. It's only a rough looksee when they're different cartridges and with different neck length/diameters. Even with the same cartridge, it's meaningless if they're not fired and trimmed to make them externally as identical as possible. Powder is useless for measuring volume.....with even the finest grain powder, fill the same case 10 times and you might get 3 identical results. Water's the only way I know to really fill a case consistently and that takes some care.

 

[Cheechako]

Ackman

Well said. :thumb:

Ray

 

[BigJim]

Cheechako You are correct, I reload, I have no interest in developing a new round type, or making my own gunpowder, or doing anything that will put me in the hospital or grave. If that makes me a reloader to use safe practice's so be it.

I don't have the time, dollars or equipment to do otherwise. I do have however the time and equipment to produce ammo that works best in my guns both pistol and rifle.

I do stick to the manuals and I feel so should those that read these posts.

Good shooting and stay safe.
Jim

 

[stiles]

Why???? What can you possibly have gained by going through all this?

Because case capacity is a useful measurement for internal ballistic calculations but case capacity + the volume displaced by a seated bullet is not useful for anything other than a relative comparisons.

 

[HPMike800]

I guess I've been away. Thanks for the input everybody. All cases fully prepped the same and fired with primers in. The point is really to cull out bad apples and get an idea of the consistency, group if necessary.

Stiles - very in depth but probably more work than I'm willing to do. I doubt in fired,trimmed,turned necks there will be much variation.

Jim - It's just case prep stuff, my loads are safe.

 

[Ackman]

Why???? What can you possibly have gained by going through all this?

Because case capacity is a useful measurement for internal ballistic calculations but case capacity + the volume displaced by a seated bullet is not useful for anything other than a relative comparisons.

******It was you with all that jibberish about measuring volume displaced by a seated bullet. You're confused. You also entirely missed the point of this thread.

 

[stiles]

Why???? What can you possibly have gained by going through all this?

Because case capacity is a useful measurement for internal ballistic calculations but case capacity + the volume displaced by a seated bullet is not useful for anything other than a relative comparisons.

******It was you with all that jibberish about measuring volume displaced by a seated bullet. You're confused. You also entirely missed the point of this thread.

Actually it was I that outlined two methodologies to NOT MEASURE THIS UNWANTED VOLUME that is displace by a seated bullet, so really who is confused?

FWIW it's 'gibberish'. Your responses have been so kind and inviting, thank you so much for elevating the conversation!,yes that's sarcasm).