checking volume of brass

[antelopedundee]

Yes but water has a concave meniscus and alcohol has a convex which always,is,precise in,overflow easy to read and get repeatable results. 10 same case weights completely repeatable

In that case I'd use the 90% isopropyl alcohol. Also, how does one dry the case before charging with powder? I'd be worried more about that. Why not just seat spent primers upside down? It can't be that bog of a deal to punch out spent primers with a decapping die, esp. if one is taking pains to make sure that all is right before going on a $18K hunting trip.

As an aside it used to be advised to dispose of unwanted primers by soaking them in oil, but I've been told that that's not always a sure thing.

 

[Steve Sheasly]

Don't mix different brands of brass? Use the same lot # of brass casings.
Then weigh brass cases.
Do you think the density of brass and the machining toletences of the extractor grooves varies substantially within the same brand and lot number of cartridge cases?

I'm not suggesting mixing different manufacturers' casings. And don't use Acme brand from the Road Runner wily coyote cartoon.

actually I do use mixed brass. once the volume measurement is matched. What difference would it make? Once the cases are prepped and made identical in size, volume, concentricities etc..

 

[Steve Sheasly]

In that case I'd use the 90% isopropyl alcohol. Also, how does one dry the case before charging with powder? I'd be worried more about that. Why not just seat spent primers upside down? It can't be that bog of a deal to punch out spent primers with a decapping die, esp. if one is taking pains to make sure that all is right before going on a $18K hunting trip.

As an aside it used to be advised to dispose of unwanted primers by soaking them in oil, but I've been told that that's not always a sure thing.

first off I do not advocate the practice of using primers that have been soaked -- but if you want to go ahead --- I have an air compressor with a dryer on it. I put the case on my scale and zero it. I dry it until it zeros again.

 

[antelopedundee]

Using 100% grain alcohol, Everclear, has it's useful advantages. But only if consumed. I'm not wasting it for volumetric cartridge case measurements.

Even that is only about 95% with the remainder being water and it's usually more expensive that 90% isopropyl too.

 

[antelopedundee]

actually I do use mixed brass. once the volume measurement is matched. What difference would it make? Once the cases are prepped and made identical in size, volume, concentricities etc..

So at what point is volume important? When charging the case and percent filled by the powder OR after firing and the expansion volume of the propellant gases? If the former couldn't that be remedied by using powders that result in compressed loads?

 

[wildcat455]

When it comes to cases, weights and volumes, I weigh every case, and spot check volumes. I use water for volume, with the spent primer still in the fired case. It was doing this that I discovered when the weights go down, the volumes go up, and vice versa. Not as much as you'd think, but enough.

I had a group of PPU cases that I intended to load up for hunting.
In 50 cases, there is a 10 grain non linear weight variation.

The only way to make this stuff consistent, was to vary the powder charge. (Well, there is another way, and that would have been at the bottom of a trash can.) After weight sorting the cases, I found a few in the middle that were really consistent. I wrote the weight of the case down and worked up a load with these. When I was done with my load development, I had an ES of 4 and an SD of 1.

If it wasn't for that, I'd have probably just tossed the cases, but I guess I needed a challenge.

I grouped these cases in 1.5 grain case weight groups. I Even color coded the heads with different colored sharpies to keep a little better track of them.

To compensate for the different case weights, I would bump the powder charge .1 grain for every 1.5 gr of case weight difference. Since I picked case weights from the middle, some would get more powder, some would get less.

(Now when I do this, I use cases at the higher end and work the powder down.)

I took a representative loaded cartridge from each case weight group, there were 5 different groups) and put them on target with a magnetospeed.
My original load for these cases was at 74 gr giving 3003 FPS average with an ES 4 and SD 1

These weight inconsistent cases, with randomly selected representative cartridges from each group, shot like this:

CW= case weight PW= powder weight

1). 238.2 CW 74.7 PW 3006 FPS
2). 239.3 CW 74.4 PW 2998 FPS
3). 240.0 CW 74.3 PW 3006 FPS
4). 247.3 CW 73.9 PW 3002 FPS
5). 248.6 CW 73.8 PW 2998 FPS
AVG 3002
ES 8 SD 4

They all went on target with 2 fliers for fouling and 3 making a .758" hole for a .450" group.

Now, is it ES 4, and SD 1 ?
No.
Is it bench rest quality?
No.

Here's my favorite question:

Is it good enough for who it's for?
YES.

I always intended these for hunting loads, and they will do just fine for me.
I worked hard on it, I'm happy with the results and I learned something along the way. You can actually vary a powder charge to compensate for changes in volume as measured by brass weight. It won't be exact, but it will be close.

 

[antelopedundee]

first off I do not advocate the practice of using primers that have been soaked -- but if you want to go ahead --- I have an air compressor with a dryer on it. I put the case on my scale and zero it. I dry it until it zeros again.

I wouldn't advocate that practice either.

 

[FURMAN]

actually I do use mixed brass. once the volume measurement is matched. What difference would it make? Once the cases are prepped and made identical in size, volume, concentricities etc..

Most brands of brass have different neck thickness which may not matter if you do not use bushing dies or if you turn necks but I will pass on mixing brands.

 

[Pdvdh]

actually I do use mixed brass. once the volume measurement is matched. What difference would it make? Once the cases are prepped and made identical in size, volume, concentricities etc..

I can think of some. Case neck thickness and tension could differ, unless you outside neck turn every single case (a prep I complete).
Mixing brands of brass is an uphill battle, unless measuring case volume is the hobby, in itself.

Mixing brands of casings seems like swimming against the tide. Backwards. Like not touching primers with fingers, but then exposing them to direct contact with rubbing alcohol, grain alcohol, or any other fluid besides air.

Cartridge brass is more than 8x denser than water. Weighing cases would then improve (lessen) the reliable and repeatable detection level in the determination of a weighed volume of brass 8x over the weighed volume of water, using the same weigh scale.

So the reliably detectable change in volume of brass can be 8x smaller in magnitude, than the reliably detectable change in volume of water, based on weight measurement alone, using the same weighing device. Advantage = weighing brass.

If the liquid you filled the cases with had a density equal to, or greater than brass, then you'd have a chance of measuring equally small volumetric change.

 

[Steve Sheasly]

I can think of some. Case neck thickness and tension could differ, unless you outside neck turn every single case (a prep I complete).
Mixing brands of brass is an uphill battle, unless measuring case volume is the hobby, in itself.

Mixing brands of casings seems like swimming against the tide. Backwards. Like not touching primers with fingers, but then exposing them to direct contact with rubbing alcohol, grain alcohol, or any other fluid besides air.

Cartridge brass is more than 8x denser than water. Weighing cases would then improve (lessen) the reliable and repeatable detection level in the determination of a weighed volume of brass 8x over the weighed volume of water, using the same weigh scale.

So the reliably detectable change in volume of brass can be 8x smaller in magnitude, than the reliably detectable change in volume of water, based on weight measurement alone, using the same weighing device. Advantage = weighing brass.

If the liquid you filled the cases with had a density equal to, or greater than brass, then you'd have a chance of measuring equally small volumetric change.

necks are turned and annealed. Not sure what the density of the brass vs water is when measuring the internal volume has to do with volume when we are measuring the material that fills the case?

 

[Steve Sheasly]

When it comes to cases, weights and volumes, I weigh every case, and spot check volumes. I use water for volume, with the spent primer still in the fired case. It was doing this that I discovered when the weights go down, the volumes go up, and vice versa. Not as much as you'd think, but enough.

I had a group of PPU cases that I intended to load up for hunting.
In 50 cases, there is a 10 grain non linear weight variation.

The only way to make this stuff consistent, was to vary the powder charge. (Well, there is another way, and that would have been at the bottom of a trash can.) After weight sorting the cases, I found a few in the middle that were really consistent. I wrote the weight of the case down and worked up a load with these. When I was done with my load development, I had an ES of 4 and an SD of 1.

If it wasn't for that, I'd have probably just tossed the cases, but I guess I needed a challenge.

I grouped these cases in 1.5 grain case weight groups. I Even color coded the heads with different colored sharpies to keep a little better track of them.

To compensate for the different case weights, I would bump the powder charge .1 grain for every 1.5 gr of case weight difference. Since I picked case weights from the middle, some would get more powder, some would get less.

(Now when I do this, I use cases at the higher end and work the powder down.)

I took a representative loaded cartridge from each case weight group, there were 5 different groups) and put them on target with a magnetospeed.
My original load for these cases was at 74 gr giving 3003 FPS average with an ES 4 and SD 1

These weight inconsistent cases, with randomly selected representative cartridges from each group, shot like this:

CW= case weight PW= powder weight

1). 238.2 CW 74.7 PW 3006 FPS
2). 239.3 CW 74.4 PW 2998 FPS
3). 240.0 CW 74.3 PW 3006 FPS
4). 247.3 CW 73.9 PW 3002 FPS
5). 248.6 CW 73.8 PW 2998 FPS
AVG 3002
ES 8 SD 4

They all went on target with 2 fliers for fouling and 3 making a .758" hole for a .450" group.

Now, is it ES 4, and SD 1 ?
No.
Is it bench rest quality?
No.

Here's my favorite question:

Is it good enough for who it's for?
YES.

I always intended these for hunting loads, and they will do just fine for me.
I worked hard on it, I'm happy with the results and I learned something along the way. You can actually vary a powder charge to compensate for changes in volume as measured by brass weight. It won't be exact, but it will be close.

this is great data and a very good test. I never thought of varying pw but it make sense and it looks like it works.
is it good enough for who its for is the answer to a subjective equation. Good question.

 

[Steve Sheasly]

Even that is only about 95% with the remainder being water and it's usually more expensive that 90% isopropyl too.[/QUOTE
Absolute alcohol: The alcohol containing water less than one percent is absolute alcohol. This is usually 99.89 percent pure. So, if 100 percent pure alcohol is available which is also called absolute alcohol. Not Absolute Vodka LOL

 

[Sika Hunter]

It is important to me to separate my once fired brass not by manufacturer or by weight (you can assume that I have done everything to the brass to make it uniform, concentric etc..) but by volume. assuming the case is in good shape and not abused volume is the only thing that will affect the accuracy. Weight is not volume and has zero effect on the powder burn characteristics threfore pressures. So lets just look at measuring volume.

I am using alcohol over live primers to measure volume. I have a methodology that has given me 100 percent repeatability for any specific case measured. My question is has anyone fired a primer that has been soaked in 70% isopropyl alcohol (yes I realize the other 30 percent is water) I did not have any 200 proof alcohol, I am awaiting an answer from CCI to see if this will damage their primers or not and for what type of non viscus liquid will work. I know this is a bit unOrthodox but if I can get repeatable volumes this way and the primers are not hurt it will keep me from having to machine a precision primer plug. I do not like the ones on the market besides it changes the volume (just a hair but it does change it) the primer used to fire the cartridge will be the saem on in the volume calc.

Hi.
I am sorting my cases by wieght rather that manufacture and have found it to very effective.
My reasoning is that brass is 9 times as heavy as water and my scales only read to 0.1 grain, so 1grain of brass has almost the same volume as 0.1 grain water which means that 0.1grain of brass has the same volume as 0.01 water. With this system I can get the greatest consistency of volume.
If you keep the allawable weight differance of the cases to less than 0.5grn then water volume differance will be 0.05grn which is better that most scales can read.
The reason I know this is that I had to much time on my hands one day.

 

[Pdvdh]

necks are turned and annealed. Not sure what the density of the brass vs water is when measuring the internal volume - has to do with volume when we are measuring the material that fills the case?

The volume of a unit weight of water, no matter which unit of weight measure used, is more than 8 times greater than the same weight of brass case material. It simply means the volume of water you're able to repeatably, accurately measure by weight, is 8x greater than the volume of case brass you'll be able to accurately measure by weight, with whatever scale you use to measure the weight.

I suppose the crux of the matter is; ... does one believe the exterior dimensions of a quality brand of brass casings, after fire-formed to your chamber, possesses exterior dimensional tolerances so poor that you'll get better inner case volume comparisons by weighing the volume of water in the case, rather than by weighing the brass case material itself. Knowing that volumetric differences in brass are much more easily detected, and that increasing brass case weight means less inner case volume.

If the cases were manufactured by Jed Clampett, or you're mixing multiple brands of cases while at the same time in pursuit of identical inner case volumes, well perhaps the answer is yes. Then it might be preferable to fill each case with liquid and then weigh the liquid weight. Or make life simpler. Discard the Jed Clampett head-stamped cartridge casings.