Case capacity by brand can vary by 8 Graines!!!

. It is very important that you repeat this process with any new container of the same powder because the powder companies allow themselves a 16% tolerance between batches. This can result in over charging if you work from the same setting and the next container of powder you get is more dense.

I have never personally seen a difference that big. But I have seen 50 fps difference on a .270 win loaded with H4831 from one lot to another.

Along those lines, I wonder how much H4831/IMR 7828 long grain differes from the short cut versions.
 
I have never personally seen a difference that big. But I have seen 50 fps difference on a .270 win loaded with H4831 from one lot to another.

Along those lines, I wonder how much H4831/IMR 7828 long grain differes from the short cut versions.

Once I have the actual volume numbers for those 50 cases I mentioned I plan to load them and soon as we get a nice day take them to the range and over the chronograph they go. I will see what I get.

As to how much the VMD differs in the short cut versions? Beats me? I would think the burn rate changes only because the powder has a greater area in short cut grains. That would result, likely in a faster burn rate. Enough to matter? I haven't a clue. Also, while the chronograph is a very nice to have tool I don't think the velocity changes represent a large pressure change but I am not sure how much the pressure and actually the pressure curve effect velocity?

Anyway, after I get the water dried out of the cases I'll remove the clay and load them and see what we get. The good part is an excel spreadsheet has plenty of columns. :)

Ron
 
Because of the popularity of Military brass, I'll throw this in the mix...
Brass as common as Milbrass it's worthy of mention.

Each brand of Milbrass (WCC, LC, etc) has different capacity,
And it's NOT in line with civilian common brass.
Older military brass has less case capacity, 'Generally'.

Since 2012, 5.56mm (LC 12 & newer) is closest to civilian brass.

There is still a BIG DIFFERENCE in 7.62x54mm military & civilian .308 Brass.
Some reloading manuals actually have different load recommendations for civilian vs. military brass (.308 cal vs. 7.62mm).

I have zero problems with using military brass, I just recommend working up loads specifically for Milbrass, and in particular up to 2011, and 2012 and later,
Watching when you change between WCC & LC.
 
Lucas McCain:
How many grains does a 3/8 by 3/8 by 3/16 volume of gun powder weigh?

Depends on the powder. Each smokeless powder has a VMD (Volume Metered Density). For example using the Lee VMD Chart Hodgdon H 335 powder has a VMD of 0.0645 so if I have a volume of 1.0cc I can say 1.0/.0645 = 15.50 grains of H 335.

Back in the very first post Mississippi mentioned H 1000 which has a VMD of about .07920 so a volume of 1.0 cc divided by the VMD 1.0/.07920 = 12.62 grains of H 1000 powder. Actually over 3 grains less than for the H 335. Then there is the other consideration of how much the VMD of powder can change lot to lot. Anyway, the weight of a given volume of gun powder will change depending on its density.

Ron
 
Equal meaning both methods are not helpful or equally helpful in reloading ?

Metal God, the answer is ..yes...:D

Both methods will tell you that one case has more, or less volume than another. That's ALL it tells you. After that, its up to you to do your load development.

I have yet to see a load manual that calls out loads by brass manufacturer.

I don't know what you're looking at, I have yet to see a loading manual that does NOT list the case use (by maker) for EVERY SINGLE LOAD THEY LIST.

Generally speaking its in the front part of the data section for each round. Along with primer used, and test firearm.
 
Lee VMD is foreign to my thinking, I operate in density.

The old Powley PSI Computer (a cardboard slide rule set) took the bulk density of IMR powder as .86 gm/cc. Ball powders are higher because they pack closer. The gravimetric density of nitrocellulose is very near 1.

The old (.30-06 era) NRA Handloading rule of thumb was that given a maximum load in a large volume case, it should be reduced by one grain of powder per 11 grains of case weight increase. It then being assumed that case volume was related to case weight and it being known that cartridge brass has a density of 8.53 gm/cc, very nearly ten times the bulk density of the powder in use.

I have trouble getting my head around these Internet Charts showing little or no relationship between case weight and case volume. If I have a heavier case of the same external dimensions as a lighter case, where is the extra mass if not in thickness reducing the internal dimensions?
 
I don't know what you're looking at, I have yet to see a loading manual that does NOT list the case use (by maker) for EVERY SINGLE LOAD THEY LIST.

Well, I could have worded that better. My point was brass cases vary from lot to lot within a manufacturer. So for example 308 Winchester, Hornady 9th Edition does cover Case: Hornady/Frontier so should I assume lot to lot and case to case that the volume of Hornady / Frontier does not vary? That or any variance will not come in light of the intended use? Speer #12 calls out IMI cases for the same cartridge. What is the likelyhood of having the called out case? How much does it matter is what I am curious about.

Ron
 
Yikes! Lots of assumptions made and questions to be answered.

Starting at the top: 300 WM has more case capacity variation than any other chambering. It's an artifact of its history, I suppose, but it is the reason QuickLOAD lists the different headstamps as if they were different cartridges, and not just a single listing you adjust.

QuickLOAD's algorithms do an excellent job of predicting pressure once you have adjusted its parameters to match actual velocity performance you get from your rifle. Without making that match, you are limited by the fact its powder database is from measurements of lots of powder the author tested without having a way to know how average those lots were. So the software does OK with giving you a reasonable range, but unless you adjust it to your chronograph readings with your gun's specifics entered in and your case's specifics entered in, you are instead estimating for an ideal test gun with whatever lot of powder Herr Broemel happened to get.

The main reason the loading industry uses pressure guns is that pressure measuring for manufacturing is a statistical QC method designed to produce ammunition safe in guns the maker well never see. Bulk powders purchased by commercial ammunition plants can come with such a wide range of burn rates, a load manual is not useful with them. A pressure gun is the only practical way to determine a safe load, and is the only way to assure conformance with the statistical QC method the SAAMI standard describes. Handloaders buy the more expensive canister grade powders which have more tightly controlled burn rate variation in order to keep load manual data valid. Many handloaders load outside SAAMI pressure standards to match their individual guns by pressure sign observation. The plant manager at Remington has no clue what rifle his customer might be able to take above the standard levels. So, you can see that loading commercially and loading at home have different concerns.

Case capacity has two standard measures:

1. Case Water Capacity (CWC): the case's water capacity left over after seating a bullet.
2. Case Water Overflow Capacity (CWOC): the case's water capacity with water level to the case mouth and with no meniscus.

The former is what people measuring case water to the shoulder are trying for. A better method is to fill a fired case with water and push a bullet in to seating depth and see how much water remains after the excess squirts out past the bullet. CWC in what you want if you are calculating load density or related parameters.

CWOC is what you want for comparing cases to see which one will have the most or the same powder capacity with all bullets. It is also what you enter into QuickLOAD, as the program also has you enter bullet seating depth information and automatically subtracts the space consumed by seating the bullet, which it shows as a result in its Usable Case Capacity output window.

Case weight does not track case capacity perfectly. I have measured a bunch of .308 brass and found difference in weight predicts the difference in capacity to an accuracy of about ±20%. There are two reasons for this limited precision. The smaller one is that different manufacturers use different brass alloys with different densities:
Code:
[font=courier new]Copper:Zinc   Density at 68°F    (notes)
   60:40        8.39 gm/cc       (aka, Muntz Metal)
   70:30        8.53 gm/cc       (aka, Cartridge Brass or 760 Brass)
   80:20        8.67 gm/cc       (aka, Low Brass)[/font]

The other factor is that case head diameters, rim thickness and chamfer dimensions, and extractor groove dimensions all have tolerances and different makers don't make them identical. These numbers can all change the weight of the case without affecting its capacity.

Case%20head%20tolerances_zpsphiablua.jpg


How much charge weight to compensate with:

Wm. C. Davis at the NRA worked this out long ago for .30-06, and QuickLOAD confirms that, interestingly enough, it comes quite close to being true for all chamberings, though it varies a little with powder choice. Roughly speaking, for each 1.8 grains of increased water capacity, you increase the powder charge by 1.0 grain. That would be equivalent to a case weight increase of about 15 grains for 760 brass if the head dimensions stayed constant. They don't. Even a single lot of brass is usually the combined output of several different sets of tooling operated in parallel to get the run done quickly.

Headstamps are not good enough to determine brass capacity. Over time, cases vary by lot. Reloadron measured Winchester .308 cases averaging 164 grains. I bought a bulk lot about 2005 that averages 156 grains. The old 1992 Palma match brass was made by Winchester, and I've been told it was about 150 grains. The Norma manual offers up one reason for this. The ammunition industry is incestuous and different members contract with other members to make different components for each other when they are short on capacity or time. Norma says it has made brass for Remington and Federal, among others, and most European brands at times, plus it is the OEM supplier of all Weatherby headstamp cases and loaded ammunition. It also makes ammunition for a number of other smaller brands. If one guy runs out of capacity or has an interruption in production for some reason, he will reach out to someone else to do it for him.

Norma, incidentally, uses 72:28 brass (approximately, and not counting other elements in the alloy).

Per Jeephammer's note, in 2012, ATK put out a call for new brass designs for military small arms cartridges, including 7.62, toward the goal of lightening the loaded ammunition by 10%. So even LC and other military cases can't be counted on to match the past capacities.
 
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Per Jeephammer's note, in 2012, ATK put out a call for new brass designs for military small arms cartridges, including 7.62, toward the goal of lightening the loaded ammunition by 10%. So even LC and other military cases can't be counted on to match the past capacities.

So what does this mean as it relates to when that should be fully implemented ? I ask because that's where my head stamps start-ish and I have a lot of brass . I'm using LC-10 tough 16 right now . I'm assuming they asked to lighten them but gave a grace period to comply .

So should I expect my LC-10 cases to weigh more then my LC-16 cases ? This specific example is 5.56 brass but I do have pretty much the same years in 308 as well .

Either way I'll weigh some of my LC-10 case and compare them to my LC-16 case to see what if any is the difference .

I'd also like to know if this is a NATO thing or just a US thing . I ask because where did they come up with the 10% lighter number ? 10% from what weight are they looking for . Is it that some NATO countries have heavier brass while others are lighter and they only really want the heavier brass weight reduced ?
 
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What is the likelyhood of having the called out case? How much does it matter is what I am curious about.


This is a yes, and no, kind of thing. It matters, and it doesn't matter. It matters that we know that different brands, and different lots of the same brand can, and do have varying case capacities.

Its about certain that the cases you have will NOT BE IDENTICAL to the cases used in the loading data. Even if they are the same brand. And even if, by some freak statistical possibility they were identical, it wouldn't matter, because you (and I) don't have the same guns.

Reloading data works, as guidelines, because the majority of components and firearms are similar. Similar, not identical. There are tolerances (variables) involved in every part of the system that play a part.

The way our guns react when fired differs from gun to gun. Most of the time the differences are undetectable, most results fall in the middle of the bell curve. BUT, combinations of variables, (stacking tolerances) also result in some being at each end of the curve.

And these things are unknowable, until discovered by testing (shooting). Which is why the manuals and every responsible writer tells us to start low and carefully work our way up.

QuickLoad, and every other program cannot take the specific variables that make your gun what it is, into account. Published loading data is an accurate and reliable report of WHAT THEY GOT, TESTING WHAT THEY HAD.

We don't have what they had. What we have is most likely very similar, but it is not identical, and there is no way for it to be identical.

A quick look at more than one source of reloading data shows it clearly. The data is similar, but not identical.

How much different your gun, or your brass, or any other factor, is from what was tested to come up with the reloading data is NOT predictable. It is not linear. Every combination of factors has the potential to combine in ways that are well outside "normal" and could be dangerous. The overwhelming majority do not, but some do. And the gun plays as big a part as anything.

As an illustration of this, here's something I experienced. 4 different guns, all shooting the same ammo (from the same box). The load was straight out of a manual (and it was a warm one, but not the max listed). A lever carbine, two revolvers and a semi auto. The carbine, the semi, and one revolver all functioned normally. the other revolver required the fired cases to be driven out of the chambers with a rod & mallet.

Extreme? yes. But it can, and DOES happen.
 
Having a hard time with this! 8 grs difference in capacity? I can't see where reloading is a safe thing to do if there is that much difference in capacity.
 
Mississippi,

Yep. Typo'd. I'll fix it. Thanks for the catch. I lent my copy of the Norma manual to someone, so I can't check, but it is actually something closer to 72:27, IIRC, with the missing percent made up of small amounts of odds and ends of things added to the alloy to help with malleability and strength.


Metal God,

It was a call for new designs that would become standard. I don't know if any have been accepted yet. As JeepHammer will tell you, ATK moved everything at Lake City over to commercial type standards. For example, they went to the European NATO country type Kistler transducers for measuring pressure after they stopped using the M11 copper crusher for pressure. But ATK moved them to the SAAMI standard type conformal transducers used in domestic ammunition making. Their objective was to make commercial production capacity more generally compatible in a shortage or when they run into a need to replenish stockpiles, as happened in 2007.


Don,

That variation is between brands, not within a brand. It's also only the 300 WM. The .308 Winchester/7.62 NATO has the next highest variation in total capacity, going from heavy foreign 7.62 military brass to light domestic .308 brass, neither of which extremes are common. Where you have the extremes, then about 4 grains capacity difference occurs. Common values in current production vary more like half that much. Brass for all other chamberings seems to vary less among headstamps. 300 WM and .308/7.62 are just two you have to watch out for. If you keep your brass segregated by lots and headstamps and load history, you'll get the most consistent results anyway.
 
Many Thank You to UncleNick for the additional enlightenment. Especially why pressure testing by SAAMI and likely CIP is done the way it is. I always wondered about that since using a software solution algorithm seems to get pretty good numbers using Quick Load.

Once I get these 50 cases filled with water and weighed it should be interesting to see how the numbers pare.

Ron
 
Don Fischer: Having a hard time with this! 8 grs difference in capacity? I can't see where reloading is a safe thing to do if there is that much difference in capacity.

My whole point when I started this thread was that you have to rework your loads when changing components. Also that recepies found in manuals, software, and on the interweb must be worked from the bottom up in your rifle....And this thread and my .300 wm is extreme but a good example to illustrate that point.

Reloading is as safe as simply shooting factory ammo, provided you follow the proper load development rules.


FIFW I have had factory ammo where primers were blown out and cases requiring a mallet and cleaning rod to remove. I have also seen a remmington 700 action with a crack in it and a 6" split down the chamber/ throat area at my local gun smith shop... Factory rifle and factory ammo.
 
I suspect that every once in awhile factory loads could be a problem, I've never seen it but I seldom fire factory ammo. I know there is a difference in the capacity of cases, Remington has always been heavier that Winchester and Norma heavier still. You are right, start low and work up. I generally start 2 2 1/2 grs low. In the past I did start at min loads but over the years I discovered it just wasn't necessary. Pressure is the first thing I look for thougth. I'll start about 2 1/2 grs low and load up at one 1/2 gr at a time to 1 gr over max. Any pressure sign, I stop. I have seem different weight to case's but not that much. Remington was always heavier than Winchester and Norma heavier than both. I have used Federal some but not a lot. The heaviest are a result of side's of the case's being made heavier, that's the deal with military case's. I only use Military cases with cast loads. I don't know how you got a difference in 8grs of capacity, that is a lot! There are loads in the manuals where there's far less than a difference than 8grs from min to max loads. Varation in brands and then in the 300mag nd 3308 case's. I've never messed with a 300 mag but in the past I have done a lot with the 308. The military case's for anything are definitely heavier, I've weight different brands of cae's in different cartridge's and the difference is there. I suggest don't weigh case's, it'll drive you crazy how much difference there is between case's in the same box. That convinced me to give it up. At about that time I was looking for improvement in accuracy in a pet 308 and that is why I started weighting them in the first place. Figured I'd separate the case's by weight. That was one idea that got blown out of the water! Military case's were overall heaviest. The difference in capacity has to be caused by the weight of the case itself. I've never en anywhere how much a given case should weight or how much capacity they should have. It's just hard to believe that there can be that much difference in capacity of different brands and still make specification's. Doesn't SAAMI decide what the standard is for each cartridge and probably how much variation there can be?
 
I don't know how you got a difference in 8grs of capacity, that is a lot! There are loads in the manuals where there's far less than a difference than 8grs from min to max loads

Don, the .300 win mag is a special extreme example. Uncle Nick explained it in a previous post but it boils down to the fact that some brands have substantially more case water overflow volume in that cartridge. The .300 wm is the reason I bought Quickload to begin with. That program allows you to specify the brand of case in that cartridge..... Because RP brass has, on average, 8 gr less volume in case water overflow than Norma, about 6 less than Winchester, about 4 less than federal and about 3 less than SAAMI.

Using RP brass in a .300wm would be advantageous using light pills pushed by finer extruded or ball powders filling the case more fully.
 
Mississippi

Blown primers happen often from (telescoping) where the headspace is short so the primer blows out first until the case stretches and pushes the primer back in, but sometimes they fall out again. Hornady factory ammo is notorious for this.

In my post about cheaply fixing flogged out primer pockets someone said there was a risk of gas cutting the bolt face but I can only imagine there's far more gas pressure with a telescoped primer scenario.


Sent from my iPhone using Tapatalk
 
This is amazing! Someone was talking about military brass. Question about it. I'm pretty sure the military doesn't make any of their own brass or bullet's for that matter. I've got quite a bit of FA49 30-06 case's. I would guess it's all made to military spect's. But could probably be made by different companies also. I've also got a few LC10 308 cases. Do these case's possibly vary as much also? If they do, it might explain why I've never had particularly good result's with military case's. I think I said earlier, I only use them for cast loads other than some LC Nat Match stuff I had at one time.

It sounds like there is no specific case capacity specification for case volume, just for outside measurement's. I would think that would leave someone wide open to law suits? I know a good number of people that load that don't give a though to mixing case's. If they are doing 300 mag or 308 and they can vary as much as 8grs difference in capacity, how come we don't hear about more blown up guns?
 
.
It sounds like there is no specific case capacity specification for case volume, just for outside measurement's. I would think that would leave someone wide open to law suits? I know a good number of people that load that don't give a though to mixing case's. If they are doing 300 mag or 308 and they can vary as much as 8grs difference in capacity, how come we don't hear about more blown up guns?

I'm no expert on chamber pressure or rifle manufacturing standards, but I am sure the tolerances are way above SAAMI MAP. Essentially you may be pounding cases out with a mallet and cleaning rod but the gun won't become a pipe bomb.

When I was developing a load for my AR-10, I was use CFE powder and LC Brass. About 1/3 of the way up the powder charge ladder I had 1 pierced primer and two that the dimple from the firing pin protruded out ward instead of in. Had I went up another ring on the ladder, the gun would not have a chance to exploded because I would have been pounding the case out with a hammer!

I'm just saying that while MAP in a .300wm is 64k, and my load in RP brass would be about 78k psi, 78k is going to cause a malfunction, but probably not an actual injury.
 
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