Pistol brass case volume

I have heard the term case volume used and have been trying to find a thread about it. I want to know mainly how concerned to be about variations in case volume between different brands the same length same bullet and coal. As it applies to accuracy.
How to measure
Currently working on 9mm and 10mm.
I have been being careful about case length and coal and pwd wt. at least one wild rd. out of 5. Is there enough pressure difference just between manufacturers due to case volume ❓❓
Thanks for your feedback.

Commercial/military brass will often be slightly different volumes due to wall thickness, but within specs. for the caliber.

Those differences with show up in increased speed and pressure causing differences in group size or vertical stringing.
Mixing and matching won't lead to you shooting your eye out, However;
That's why its so common to keep the same head stamps on a group of reloads if you're trying for a little bit of extra accuracy.

Since I'm not shooting for the Bianchi Cup-- I don't sort pistol brass.
But do on rifle cases out of habit as much as anything.

It's not mentioned in the newer reloading books, but the old ones recommended you to reduce your charge by a grain or so
in using commercial case loading data when using military brass that had a thicker wall on the case.
They said the less volume in a GI rifle case would bump your speed & pressure up over the given data in the loading books.
It was no big deal until you got up around the max. charges, but it'd effect your group size if you mixed in civilian brass.

For starters I havent worked with 10mm. But 9mm there is a headstamp that has a big step within the case. A simple glance inside the case shows how obvious it is. I found this on the net.

Attachment 309635

This could ruin your day...

But when im sure I dont have any of these I load em up. I dont spend a much time near max loads, so I try to keep a lid on my OCD.:Fire:

You will likely get some very detailed answers from others-- but I'll get it started. Under normal circumstances, for a pistol, standard commercial brass will not have enough volume variation to matter much from one manufacturer to another. However-- there are some things to watch for. At lease one manufacturer puts a sort of step in their brass on the inside (at least for 9mm)-- and that reduces the volume significantly. Watch for that brass and don't use it. If you are worried about repeatability of your rounds, sort your cases by headstamp and load all the same headstamp in each set-- that will minimize volume differences. Military brass may also be different-- but I don't use much of it so hopefully someone else will chime in on that.

Personally, I have loaded and fired load sets in 9mm and 45 acp using a mix of commercial brass and not noticed any difference in accuracy, but I only shoot pistol offhand, so any differences probably get lost within my own ability to be accurate. I have noticed small differences with 38 Special and 357 Magnum, so I use matched headstamp brass sets for them.

And just in the time it took me to type this up the above two posts popped up showing, among other things, what I was talking about (including the stepped cases)

Case volume is normally measured with water although some use fine ball powder. Water is the universal standard so it can be compared to others results and measurements. If you use fine ball powder it's mostly just to compare one case to another.

Like anything the more consistent the more accurate. That being said common sense goes a long way. Some go way overboard sorting and weighing components. Nothing wrong with that unless it takes away from actual trigger time. For most shooters and applications the accuracy differences minor case volumes will not be noticed. There are some exceptions like 308/30/06 GI brass verse commercial. With those the volume difference may be enough that loads may need to be reduced 10%. For 223/5.56 that usually is not the case unless it's some oddball foreign military. Same goes for the odd foreign commercial stuff. Some of it is very different than the major US standards.

People tend to have very strong opinions on this subject. That always surprises me since it's so easy to test. Just compare groups with mixed headstamps verse non-mixed. I have tested this repeatedly with a variety of rifle and pistol calibers. With the 223 using mixed headstamps I still can hold 1/2 MOA 10 shot groups out to 300 yards used LC, Winchester, Federal, Remington and IMI brass out of my better rifles.

https://forum.accurateshooter.com/th...brass.3783944/

These responses are what my common sense tells me but my common sense usually needs some help. I’m also stressing over case length how it varies the oal. And how much the difference in boolit seating depth can affect pressure. And knowing that if all my Boolits weighed exactly the same Yana yada. I have been separating +- .5 and +-1gr. Mostly with in 1 gr. So many variables so little time. I just want to start a production run. Thanks for the help.

Here in Alaska it’s 10.30pm pacific 11.30. East Coast 2.30am. just saying I didn’t expect any one to respond so late.

Like most of us here, I'm retired and keep odd hours.
Coming here also helps keep me out of those crooked BINGO parlors.

Case length shouldn't effect OAL.
The ram holds the bottom of the case, the seating stem acts on the top of the boolit, or just below the top.
Between the two--- they don't know, or care how long or short the case is.

Case length will have some effect on the crimp if the cases aren't real close to being all the same for what the
the crimp die is adjusted to. A taper crimp will minimize this.
A roll crimp is problematic is you run different case lengths through it.

Not sure where, but there's a good thread here running now on weighing and sorting out boolits.
Check it out. It'll answer a lot of your questions.

Quote:

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Originally Posted by Mandoair

These responses are what my common sense tells me

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Stay with the published data, and read up on what's in the front end of loading books like Lyman's
and you won't get into too much trouble.

The folks that make a mess are the ones that jump off into uncharted waters early in the game,
or start at max. loadings and work up trying to make Grandpa's old .30-30 into a .300WinMag.

My $0.03
I have weighed lots of "military" brass that was Lighter than Commercial...some by Plenty...so...I take some of That with that grain of Salt..
tho, maybe the weight of the brass, and the Capacity are Not related!!
What is sometimes a concern, is loads of something like H110/W296 powder, in yer handgun loads. Hodgdon claims (used to anyway) that these should Not be reduced much more than 80% of available capacity... Only reason I bring this up...is , available capacity can be Quite different with 2 different Boolits of the Same Weight, but different Nose Configuration... Sometime I need to get anal and actually check how much Boolit is In the Case... just to keep me at ease, with myself!

I have bulged a few cases and super-flattened primers in Bullseye target loads for my S&W Model 52. Troubled and fearful I might "blow" this cherished firearm (not to mention hurting myself or others!), I (as soon as my pulse returned to almost-normal ;)) quested, "WHY???". I was using -- to the .0001 -- published data. Here's what I found to be the source: The 148 grain my-cast wadcutters had a button-tip. When seated just that (me guessing here) ~3/32" deeper than a flat-topped bullet -- did this! (My solution? SAME bullets, same brass, same primers -- 'cept I loaded the bullets upside down, with the button at bottom. No more flattened primers, or other analomies -- and -- bion -- my score at target even went up almost a smidgen!)
I soooo agree with what Winger Ed wrote -- Posts #2 and #7 here-above -- and wished to share -- in my case -- what a rather small difference in case volume results can do.
Geo

Quote:

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Originally Posted by georgerkahn

-- to the .0001 -- published data.
Geo

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.0001 of what? Grain? Inch? How are you measuring whatever you are measuring?

Your experience points up why going by OAL when reloading anything is such a minefield. Especially so with small volume pistol cases running at high pressures, e.g. 9mm, 10mm. OAL data is only valid for the specific bullet used to generate it.

Quote:

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Originally Posted by M-Tecs

.0001 of what? Grain? Inch? How are you measuring whatever you are measuring?

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M-Tecs -- my apologies as communication has never been one of my fortes :(. I had meant the phrase to indicate me being as precise as possible duplicating printed data -- be it weights, depths, OALs, etc., etc., to hopefully have been read as, "--- to the one ten-thousandths (of anything/everything: be it case length, bullet size, bullet weight, seating depth, powder weight, etc., etc., or, etc.) ---".
Best!
geo

With the exclusion of obviously issues, such as the stepped brass pointed out above, I have found very little difference between headstamps in handgun cartridges. Groups shoot more accurately than I can shoot with a pistol. And I can regularly place groups within a 2-3" grouping at 100yrds out of a PCC. For a cartridge of that size I do not think it matters too much in most cases. What I HAVE found to matter is loaded round to loaded round consistency in charge and OAL. Obviously some cases will have +/- a little bit of capacity. But as long as we maintain as consistent a loading proceedure as possible (also removing the obvious example as above from our process) we should expect remarkedly accurate ammo. Though sometimes vertical stringing can been seen at a distance. Most of the time I find my 9mm loads to be much more accurate than factory ammo of similar design: such as my 115 FMJ load against Winchester White Box. I attribute this to attention to detail and my consistency while reloading versus factory loaded ammo which is probably loaded to "close enough" standards. The fact I'm using a turret press with a auto-disk probably helps.... But at the end of the day, I don't think the average person needs subMOA accuracy with a pistol cartridge. I'm not even sure if that can realistically be done to any practical standard.

Quote:

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Originally Posted by georgerkahn

M-Tecs -- my apologies as communication has never been one of my fortes :(. I had meant the phrase to indicate me being as precise as possible duplicating printed data -- be it weights, depths, OALs, etc., etc., to hopefully have been read as, "--- to the one ten-thousandths (of anything/everything: be it case length, bullet size, bullet weight, seating depth, powder weight, etc., etc., or, etc.) ---".
Best!
geo

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Accurately measuring to .0001 of an inch beyond the capabilities of most unless they have a gauge lab at their disposal. Weighing to .0001 of a grain is fantasy land. Scales that have .01 of a grain resolution start at about a $1,000.00. Scales that have the ability to weight .0001 of a grain will be much more expensive. Same for the temperature, humidity and air flow-controlled room required to house a scale that accurate.

Yes I know lots of mics have tenths graduations on them. Reality is most people are plus or minus .001" will a good dial caliper and plus or minus .0005" with a mic. When using a mic with a gauge block or a deltronic pin plus or minus .0002 is realistic for the average person. Skilled users plus or minus .0001 may be possible with heavy on the may be possible. When tolerances get that tight the skilled users generally switch to more accurate inspection methods. Indicating or pressure mics with gage blocks or Deltronic pins as standards will get you there for about $800.00. The standard ZZ gauge pins have a .0002" tolerance so they are not usable as a standard for that level of accuracy.

https://www.meyergage.com/abcs-of-ga...sses-of-gages/

https://deltronic.com/

More trigger time is the most beneficial component of improving accuracy. Time spent to produce reloads to an unrealistic tolerances has little benefit and if those efforts take away from trigger time they are detrimental to accuracy.

Quote:

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Originally Posted by Winger Ed.

Stay with the published data, and read up on what's in the front end of loading books like Lyman's
and you won't get into too much trouble.

The folks that make a mess are the ones that jump off into uncharted waters early in the game,
or start at max. loadings and work up trying to make Grandpa's old .30-30 into a .300WinMag.

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This is great advice for anyone beginning anything: stay within published guidelines.

At some point, many people might believe that they don't need to. Perhaps that person might be OK for quite some time, more likely they have an experience they wished they might not have had while learning on their own this way. Then, as they learn more, they find information from reliable sources that would have substituted for their hard paid for personal experience.

There is a room for exploration, don't get me wrong, but a person really needs the background to start the process or be willing to pay for lessons in unappealing ways.

I have done it both ways, and later was left wondering why I tried some things I did, and was thankful in some instances that I and others were left w/o injury. The flip side is some things were found through the experience of others, or writings, only many years after what I learned myself & put to use. Good & bad available in the 'try it' approach for sure.

Comment #9 on the military brass: (Yes) often it is stated and repeated that military brass DOES have less volume than commercial. I am not so sure about the general usefulness of that statement either because I once undertook the effort to weigh commercial Winchester & RP 30-06 brass from the 1950s (WW Super X, if I remember), 1960s, 1970s & 1990s (Both Win & RP) and a smattering of Military (HXP Greek from late 1960s, couple samples DEN & LC from unremembered dates that could have spanned 40s - 70s), and found that as commercial brass was made over these decades it generally has gotten heavier. The problem with this approach was: not definitive (small sample of military, and commercial wasn't really dated) and only applied to 30-06. So, rather than disregard the general statement, I will often just weight some brass if I am exchanging some and I am using a very different supply to do so. I will say though that some different samples I had in that 30-06 brass varied (by memory) a good 5-8% in internal volume -- 2-3 grains of a charge would spill over some cases while the full charge was down in the neck of others when I did a '...dump in the powder and see what happens...' check of volume against the weights.
The Norma manual I have even specifies 2 different sets of load data for 300 Win Mag because of different brass lots (with different construction) that they produced.
Page 308 of Norma manual 2004.

There is also conflicting info about do's & don'ts on W296. I have seen '...don't reduce more than 10%...' and published data in manuals where start to max is 25-30% spread (that was a thread on here months ago). Manuals are reliable in most instances, as there is significant liability not only monetarily, but also in reputation.

Stay with the data for the bullet provided, and watch what you're supposed to watch. Good advice.

The measurement comments in #15. All I can do is smile.
It is amazing what precision people think they have, and not realize they don't. This spawns entire industries w/ calibration, certification, math (statistics), process control, science (not same as Math, as the concept of significant digits isn't really math, but based on math by my memory), etc.
Also, I think it misguided to nit pick over even several thousandths of an inch in COL in most cartridges, certainly bottleneck rifle cases where a load isn't very close to the lands. There is here an entire process developed around measuring to ogive in match ammo because point forming on even really good match bullets varies. Let alone exposed lead points on things like a hunting bullet after they have been poured over chutes in manufacturing into bins and then bounced around in boxes to reach a user's doorstep.

Being precise is Very good. Being a sloppy reloader invites lots of problems.
Believing precision exists where it does not is humorous from the outside, and an opportunity to learn more about what goes into the whole process from the inside.

I could give a funny story about grad school and a peer agonizing over interpolation of emperical tables to get values to plug into complex heat transfer equations, but just suffice to say that after he expended his ire on my approach, our prof (30 yrs ago) did an example problem on the chalk board, and said '...now don't agonize over interpolating the table, the value you want is about 1/2 way between these two numbers...'. I had a grin, my peer scowled.

Thanks for the picture, it's clearer to me now.

For accuracy. 1 lot, same brand, fired same amount of times. Ask any old Bulleseye Pistol shooter firing at the 50 yard line.

Quote:

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Originally Posted by uscra112

Your experience points up why going by OAL when reloading anything is such a minefield. Especially so with small volume pistol cases running at high pressures, e.g. 9mm, 10mm. OAL data is only valid for the specific bullet used to generate it.

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Thanks I never thought much about oal just kept it at the book value until I was working on a rms 145 9mm plated. After a few strings of those rounds I started to wonder why things didn’t seem right. Turns out the oal of 1.130 made a very slight interference fit in the chamber. They fired but signs of high pressure and wild groups. Shorting those to 1.020 helped and got me to thinking about other variables. I put those bullets on the shelf in favor of the MP 136/138 130. No lube grove PC. Liking those. Thanks for the words on consistency even to times fired. Don’t think I’ll go that far though.

Nineteen posts and not one of them touched on actually measuring case volume.

The way I do it, is to take a clean case and place it on my scale. Zero the scale. Take a syringe and fill it with distilled water. Begin dropping water into the case with the end of the needle at the bottom of the case. This prevents any possible bubbles from forming on the interior of the case. You may or may not need to plug the flash hole in the case to prevent water leakage. As you fill the case with water begin pulling the end of the needle up to the top of the case. Using distilled water and a clean case I haven't had to worry about a meniscus forming on the top of the case, which could add a bit more mass. Once full, the scale will show the total case capacity in grains (water weight). Repeat for as many cases as you'd like to form an average for a certain batch. Having quantitative data for case volume is helpful if you're using Gordon's Reloading Tool, Quickload, or the Powley Calculator to work up starting loads or even calculate the effects of a change in case volume.