Figuring case fill?

bigfelipe

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Is there an online calculator that will tell you the case fill of various calibers and powders if you insert the numbers?
 
Im not aware of one, and it would be tough to do because cases vary by manufacturer. Lee has volume ratios for powders in their book. You could measure your case and develop something specific to your cartridge and headstamp. For what purpose though?
 
Percentage/volume of powder fill in case while reloading.

Start by measuring total case capacity. Fill the empty case with water, then measure the amount if water needed in CCs. A syringe works best. That gives you total case volume.

For the powder capacity, I use the lee powder scoops. They are graduated in CCs too. I get the load I want, in grains, I then I figure out which scoop fits the load. That gives me the volume of powder.

With those two numbers, you do the math and that will give the fill percentage.

If only done this a few times and a very long time ago.
 
Start by measuring total case capacity. Fill the empty case with water, then measure the amount if water needed in CCs. A syringe works best. That gives you total case volume.
Are you seating a bullet and then filling through the flash hole?
 
Start by measuring total case capacity. Fill the empty case with water, then measure the amount if water needed in CCs. A syringe works best. That gives you total case volume.

For the powder capacity, I use the lee powder scoops. They are graduated in CCs too. I get the load I want, in grains, I then I figure out which scoop fits the load. That gives me the volume of powder.

With those two numbers, you do the math and that will give the fill percentage.

If only done this a few times and a very long time ago.

Problem is I'm working from the other direction... Don't have a load or a bullet yet. I have this...

Case capacity 1.56 cm3 (24.1 gr H2O)

And case OAL, cartridge OAL. Working from that and known loads of similar size in say 45acp (25gr H2O and lower pressure), I have to figure out the math on a starting point.
 
Problem is I'm working from the other direction... Don't have a load or a bullet yet. I have this...

Case capacity 1.56 cm3 (24.1 gr H2O)

And case OAL, cartridge OAL. Working from that and known loads of similar size in say 45acp (25gr H2O and lower pressure), I have to figure out the math on a starting point.

You're out of my depth of knowledge.

A lot of people have spent the money on the quickloads program for there computers. It usually gives enough info to get you a starting load and a "dont go there " load.

You could try over on castboolits.com. There's a lot of folks that will help get you a starting load.
 
Nope, just figuring the percent of powder volume to total case volume.

Why? How will you use this information?

There are so many variables to consider that direct measurement may be the fastest and most accurate route.
 
For rifle loads other than 300blk, I weight. For pistol loads I just find a cup that gets me in the sweet spot with a powder and do 5 or so test weights. I get withing a tenth or two every time. Not even sure why I care about case volume.
 
I think Quickload can calculate that. There are some manuals that give approximate fill percentage. Others simply put a C which stands for a compressed load but that is only for the brand and lot they used for testing.

There is a new one that is free (Quickload is a program that you buy) that might also calculate fill percentage called Gordon's Reloading Tool. I've seen a few introductory videos that can be found on YouTube but haven't downloaded it to try it out.

If you do try it and it does all that, spread the word.
 
Nope, just figuring the percent of powder volume to total case volume.
Don't see where this will help much. It doesn't take into account the volume taken by the bullet when seated. To me, when load data says 100% case fill, that means the powder fills the empty volume with the bullet in place. Anything more than that will be a compressed load, which is sometimes listed as a percentage number greater than 100%.
 
Don't see where this will help much. It doesn't take into account the volume taken by the bullet when seated. To me, when load data says 100% case fill, that means the powder fills the empty volume with the bullet in place. Anything more than that will be a compressed load, which is sometimes listed as a percentage number greater than 100%.


Now that you've got me thinking, you could calculate the volume of the bullet that's in the case. Subtract that from total case volume and that would give you free case volume number. The books will give you bullet diameter, oal length of the bullet, cartridge oal. At least with a flat base bullet.
 
Don't see where this will help much. It doesn't take into account the volume taken by the bullet when seated. To me, when load data says 100% case fill, that means the powder fills the empty volume with the bullet in place. Anything more than that will be a compressed load, which is sometimes listed as a percentage number greater than 100%.
Now that you've got me thinking, you could calculate the volume of the bullet that's in the case. Subtract that from total case volume and that would give you free case volume number. The books will give you bullet diameter, oal length of the bullet, cartridge oal. At least with a flat base bullet.


That's the point of this thread. I am designing a bullet for 10mm and I'm trying to see what kind of uncompressed load I can fit under it. I know how much space the bullet takes up. So now I'm looking for a powder load that can push the bullet safely and only take up about 25% case capacity.
 
Nosler publishes case fill % on all of their data. It helps me pick out powders for new and untested loads in some cartridges.
 
That's the point of this thread. I am designing a bullet for 10mm and I'm trying to see what kind of uncompressed load I can fit under it. I know how much space the bullet takes up. So now I'm looking for a powder load that can push the bullet safely and only take up about 25% case capacity.
Send us 100 bullets of your choice and 20 pieces of brass. Include your choice of powder and velocities desired. We will take it from there.
 
That's the point of this thread. I am designing a bullet for 10mm and I'm trying to see what kind of uncompressed load I can fit under it. I know how much space the bullet takes up. So now I'm looking for a powder load that can push the bullet safely and only take up about 25% case capacity.
Only 25% case capacity? Normally we look for a lot more case fill than that, at least enough that a double-charge is not possible. When you are at 25% capacity, then you can have a problem with position sensitivity. Some powders have a large difference in velocity depending on whether the powder is at the front or rear of the case when the primer fires. Just recently, I saw that problem with Sport Pistol powder in 45acp, over 100fps difference, and it was a lot more than 25% case fill.
 
Only 25% case capacity? Normally we look for a lot more case fill than that, at least enough that a double-charge is not possible. When you are at 25% capacity, then you can have a problem with position sensitivity. Some powders have a large difference in velocity depending on whether the powder is at the front or rear of the case when the primer fires. Just recently, I saw that problem with Sport Pistol powder in 45acp, over 100fps difference, and it was a lot more than 25% case fill.

25% for the powder because the projectile will take up nearly 75%
 
25% for the powder because the projectile will take up nearly 75%
Ok, 25% of the empty case. That makes more sense. But, I have to wonder how big the bullet is that will take up 75% of a 10mm case. :eek:
 
Case capacity % on a loaded round is the amount of space the powder takes with the bullet in the case at the COAL.


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