Case Capacity Difference By Brand

[trevj]

Learn what you can about the tools used to actually make the cases and you will be a long ways ahead in understanding why there is a variation.

The tooling used to form the blank cases is under a great deal of stress and wears in use, then gets replaced as required. The accuracy to which the tooling is made, as well as the accuracy with which they tools are matched when more than one line is feeding into the bin of formed cartridges, determines the consistency of the results, along with a bunch of other variables.

About the only thing you can say for certain, is that it varies, and if you want to know, you need to measure what YOU have, and keep notes.

Oh yeah. Anyone that follows the advice of a random poster on the interwebs, without cross checking their info, gets what they deserve.

Cheers
Trev

 

[H4831]

With all this talk about case weight/capacity affecting pressure in the cartridge, I wonder how many on here have actually made tests, to determine if variation in case capacity actually does change the pressure, or is it just another of the many unproven theories on gun blogs.
For the 243 I once had Federal cases which were ten to twelve grains heavier than the 243 Winchester cases I was also using. After reading a thread such as this one, I decided to test. So I loaded five of the lighter Win. cases and five of the heavier Federal cases with 46 grains of 414 powder and 75 grain Hornady HP bullets and fired each group of five over a chronograph, allowing the rifle to cool between groups, just to eliminate any variance I could.
The velocity for all was over 3500 fps, but the lighter Winchester cases with more powder capacity, which, according to the theories I read on here, should have made the lowest velocity, actually averaged 20 some fps FASTER, than did the heavier weight Federal cases!
Thus, I continue with my practice of treating all cases as being of no difference in pressure, unless they are of considerable more variance in weight, than about ten grains in 243 size cases and don't worry about larger variations in larger cases.

 

[SND]

The difference is definitely apparent at long distances with match rifles.
Same thing as shooting a round that was already fire formed and is closer to the chamber size, then one that is from new unfired brass, vertical normally changes even if its the exact same load and brass lot/weight.
A 243 may not show it quite as much as a 308.

Chronographs don't mean much compared to what shows up on paper at the other end.

 

[H4831]

The difference is definitely apparent at long distances with match rifles.
Same thing as shooting a round that was already fire formed and is closer to the chamber size, then one that is from new unfired brass, vertical normally changes even if its the exact same load and brass lot/weight.
A 243 may not show it quite as much as a 308.

Chronographs don't mean much compared to what shows up on paper at the other end.

The question was about different pressures with different weight cases and did the difference make them unsafe.
Pressure equal velocity, so a chronograph is the meaningful way to test pressures/safety.

 

[trevj]

With all this talk about case weight/capacity affecting pressure in the cartridge, I wonder how many on here have actually made tests, to determine if variation in case capacity actually does change the pressure, or is it just another of the many unproven theories on gun blogs.
For the 243 I once had Federal cases which were ten to twelve grains heavier than the 243 Winchester cases I was also using. After reading a thread such as this one, I decided to test. So I loaded five of the lighter Win. cases and five of the heavier Federal cases with 46 grains of 414 powder and 75 grain Hornady HP bullets and fired each group of five over a chronograph, allowing the rifle to cool between groups, just to eliminate any variance I could.
The velocity for all was over 3500 fps, but the lighter Winchester cases with more powder capacity, which, according to the theories I read on here, should have made the lowest velocity, actually averaged 20 some fps FASTER, than did the heavier weight Federal cases!
Thus, I continue with my practice of treating all cases as being of no difference in pressure, unless they are of considerable more variance in weight, than about ten grains in 243 size cases and don't worry about larger variations in larger cases.

I think, in all honesty, a fella could spend a lifetime in a research lab with a pretty much unlimited budget, and not really reach the bottom of the variables which affect the smaller portion of the equation (aka, the differences from one to the next).

Tiny differences in alloy content, tiny differences in hardness of the neck, tiny differences in the pause between the up and down strokes of the press, etc,. are all possible contributors to differences in the end result. And those are just a few of the variables that might affect neck tension, off the top of my head. I am sure it is NOT a definitive list!

I have better things to do with my life in general, than to worry about the tiny differences, and most guys that are obsessing over them before they ever get going reloading, should just muckle on to the program and load some basic ammo and take it out shooting, IMO. Use the Lee Scoops, with the Lee charts, and you have serviceable, safe loads. The time spent obsessing is better spent shooting. Choose the correct powder and bullet combination, and you don't even need the scoops, as there are quite a few combinations in which it is not physically possible to put enough powder in the case, to reach unsafe pressures. Fill the case, level it off with a business card, seat the bullet. Precision? Nope. But the deer won't know!

When the shooting gets past the point where the ammo becomes a limit, then is a GREAT time to start worrying about making it as near perfect as you can.

Was it Voltaire that said "Perfect is the enemy of good!"? Seems appropriate. Good first, perfect later.

Cheers
Trev

 

[H4831]

Trev, You have put into appropriate words what I have said in dozens of posts on here.
Bruce

 

[trevj]

Trev, You have put into appropriate words what I have said in dozens of posts on here.
Bruce

At risk of forming a mutual admiration society, thanks!

I have a pretty high opinion of what you have posted around here too.

Not so much dumpster fire, if you don't throw too many matches into the mix, eh?

Cheers
Trev

 

[Ron AKA]

With all this talk about case weight/capacity affecting pressure in the cartridge, I wonder how many on here have actually made tests, to determine if variation in case capacity actually does change the pressure, or is it just another of the many unproven theories on gun blogs.

Case capacity obviously makes a difference. If it didn't then you would get the same performance out of a .22 Hornet as you would out of a .22 Swift. The only question is whether or not you can measure a small difference, or care.

 

[BigUglyMan]

I have been reloading for over 50 years. If you want to know the weight of the brass, then weigh the brass. If you want to know the volume of the case then fill the case with powder, and weigh the powder. When you fill one case with powder then dump it into the next case after you have weighed it. Speeds the process up. Some do it with water, but I find that very messy.

Remember it is the volume of the case that affects ballistics, not the weight of the case.

Yes. and if the cases are FL resized and trimmed to the same length they will have the same outside dimensions. That being said, the case that weighs more will have less capacity. I fail to see why you would have to screw around with powder or water.

 

[Ron AKA]

Yes. and if the cases are FL resized and trimmed to the same length they will have the same outside dimensions. That being said, the case that weighs more will have less capacity. I fail to see why you would have to screw around with powder or water.

Some people want a case capacity to use as an input for QuickLoad. Unless you are a real math whiz, the only reasonable way to get it is to fill the case with powder or water. Yes, if you just want to sort your cases, weight will probably do. Here is a picture of a weight sort I did.

Also a practical issue is what kind of scale you have. It is a real pain to use the water method if you have a balance beam scale.

 

[bigedp51]

Also a practical issue is what kind of scale you have. It is a real pain to use the water method if you have a balance beam scale.

Now I know where your 50 years of reloading experience comes from, you added your scales age to inflate your minimal experience.

I hope you know that newer Redding scales have magnetic dampening and are green.