I was given 65 once fired 300wm RP cases in a paper bag. Cleaned, resized, trimmed and cleaned again. Then I screwed up and weighted them. They range from 242.1 to 244.8 grains. I seem to recall that cases should weigh within 5% of each other. Thats 12 grains. Is that 5% figure correct? If it is, then they are matched. Right? If not then what is the figure? These will be mid pressure loads in a Savage 110 hunting rifle that shoots just about everything below 1.25 moa. Man I feel like I am way over thinking this.

You are over-thinking it.

quote:

Originally posted by dick broussard:
I was given 65 once fired 300wm RP cases in a paper bag. Cleaned, resized, trimmed and cleaned again. Then I screwed up and weighted them. They range from 242.1 to 244.8 grains....

Hey Dick, You did a good thing by weighing the cases. Now you know they are extremely close to being exactly alike.

I really don't remember weighing "ANY" R-P cases recently in any Lots similar to that size and having the weights that close together.

I do one more "sort" when shooting. If I have an unexplained Flier, I mark that case. Then see if it does it again. If it does it the second time, the case is relegated to Pressure Detection loads.
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Huuummm, You could have "screwed up" if you had intended to use, "Bad Lot of cases!", as an excuse.

Sounds like someone did a fairly close sort on that brass already (less than 3gr from hi-lo). Load it and go hunting.
Last time I weighed RP brass, out of 500pcs of 30-06 brass I kept 250 that were within +/- 5gr of average (those got sorted into seperate "lots" later), the rest I gave away. I had a Min-Max spread of 70gr (yep, seventy grains).

Weighing cases will prove nothing, other than you know how to use your scale.

It is the case capacity that makes a difference.

quote:

Originally posted by ricciardelli:
Weighing cases will prove nothing, other than you know how to use your scale.

It is the case capacity that makes a difference.

am i missing something you are saying ? won't cases of significantly different weight (assuming identical external dimensions) have different capacity ?

If external dimensions are the same would that not make the weight difference in the internal capacity?

I have found no value in weighing cases. I can buy a bag of Remington brass and resize them before loading and they all shoot perfect tight groups under 1/2". I shoot with some guys that weigh their brass and do alot of other little things they think is important and they don't shoot any better than I do. I think people read and try new stuff and then like to talk big about their technigue. Then it becomes a "keeping up with the Jones issue". Just my opinion until one of those guys can prove me wrong.

Case weight had no relationship to case capacity...

The weight of a case can vary because of the alloy used, it can vary because of the mass of the head of the case, it can vary for many reasons.

quote:

Case weight had no relationship to case capacity...

Boy does that ever indicate someone doesn't know what they're talking about!!!!

Yeah, you're absolutely right, Bob, I have no frigging idea about reloading.

I'm outta here!

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Some years ago I bought a second-hand 6PPC, and included with it were some Sako 6PPC USA cases. Most of these cases weighed between 123 and 124 grains, empty and un-primed, and using them, I finally settled on a load of 27.5grs of a certain powder, with 70gr bullets. It was as hot a load as I was prepared to use - with any heavier charges, the cases became a bit hard to chamber after 3 or 4 loadings, neck-sizing only.

Some time later I acquired some Norma 6PPC USA cases. These weighed about 106grs, empty and un-primed, and held approximately 2.2grs MORE fine-grained powder than the Sako. Using the same powder and bullets as I was using with the Sako cases, I had to increase my charge to 30.0grs (2.5grs MORE!) to obtain similar velocity and accuracy. (and similar pressures, judging just by outward appearances)

Anyone want to try to convince me that the weight of cases bears no relationship to their capacity, and should be disregarded?????

Imagine what might have happened if I had initially worked up my load with the Norma cases and then blithely gone ahead and used it in the Sako cases, with no further ado. Frankly, I prefer NOT to think about it too much!

The worst could not have actually happened in this particular instance, because there is no way that 30grs of powder would have fitted into the Sako cases. However, if I had been using a faster burning powder, with which, say, 26 or 27grs was a maximum load in the Norma cases, and then put this load in the Sako cases ...

I have encountered similar weight/capacity differences in 308 Win cases, too, with some of the lighter commercial cases weighing around 165grs empty and un-primed, and some of the heavier military cases weighing well over 180grs. The lightest cases needed powder charges about 2grs more than the heaviest to achieve similar velocities.

Steve can depart this discussion in a huff if he wishes, but I will continue to weigh my cases, and keep notes of same, so that I can have a fair idea of what to expect from them.

I will readily concede that I have never been able to prove that weight variations of just a few grains, within a batch of cases of the same brand and lot, makes any discernable difference to either accuracy or velocity. But - I still want to know what weight and capacity range each lot of cases I have falls in.

quote:

Originally posted by ricciardelli:
...The weight of a case can vary because of the alloy used, it can vary because of the mass of the head of the case, it can vary for many reasons.

Hey Steve, Are you saying you sort by "Volume" or don't sort at all?
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I can see where going through a Full Case Prep, plugging the Primer Pocket with something(upside-down spent primer?), weigh the empty case, fill it with water and weigh it again would determine the Volume for comparison. And no doubt, that would provide an even better comparison of all the Cases in a Lot.

As much as I mess with getting all my cases "nearly alike" by weight Sorting, doing the old Water Volume Comparison is something I'll pass on.

Of you guys that do sort your brass by weight, how much standard devaition do you have form the mean weight, is 2 grains to much high and low for a total range of 4 grains?

quote:

Originally posted by ricciardelli:

The weight of a case can vary because of the alloy used, ................

Steve doesn't believe in sorting by weight. He's said it many times in many places.

FYI cartridge brass is ALL 70/30 alloy. Any traces of anything else won't affect weight and capacity to any discernable extent.

I'm not a statistical freak so can't address the issue of standard deviation. However, I do weight sort my brass AFTER fire forming, trimming and prepping. I also check internal volume of the brass by checking water capacity. There can be as much as 5g difference in water weight between the brass in the same lot, which is significant. At some point when checking water weight I determined that variance of a couple of grains or less of water weight didn't matter a whole lot in a hunting rifle and established my own criteria for sorting. If the weight of the brass varies by no more than ± 1% of the mean weight of the lot, it's hard to discern any difference and that's the standard to which I sort.

In the larger cases with which I mostly play, the larger belted magnums and WSM's, that means about 3-4g difference in dry weight. Any more than that you'll see a difference in chronographe and in group size in my experience.

Croberts
In a factory hunting rifle, +/- 10gr (form average) isn't noticable by the average shooter. Now with a tuned custom rifle, the right shooter 'might' notice the difference, and with a match gun the right shooter 'will' notice it.
However if you put Joe Average behind the match gun, he probably couldn't tell the difference between matched brass and streight run brass.
It's a tripod effect, with the shooter, the ammo, and the rifle forming the 3 legs. If one falls short, the whole system falls short.

Before I go any further, let me recognize Bob338 as the guy that convinced me about marking the cases that have "Fliers". I've known him a long time and though is "taste in rifles" is poor , he knows a good bit about Reloading, driving long distances at HIGH Speeds and hunting Elk in that old snow. Make that BIG Elk!

quote:

Originally posted by Croberts:
Of you guys that do sort your brass by weight, how much standard devaition do you have form the mean weight, is 2 grains to much high and low for a total range of 4 grains?

Hey Croberts, I agree that it depends on the capability of the rifle, meaning the distances you intend to shoot accurately. And the size of the Case.

For example, I have a 444Mar which will be used inside 150yds and primarily inside 75yds. Weight Sorting those cases might get done just for grins, but the + or - 10gr that Tailgunner mentioned would concern me less than if a Case creates a Flier.

Then lets say you had a 223Rem and a 7mmMag. The difference in those case weights can be from about 9Xgr to say 24Xgr. Lets say you had a 2gr variance in your 223Rem cases and that would be a bit more than 2% of the case weight. Where the same 2gr in the 7mmRemMag is less than 1% of the overall case weight. Simply mentioning it for you to think about.

The real Test comes when you shoot some groups with cases known to be wide apart in weight as the + or - 10gr previously mentioned. As you read through these posts, some will tell you it does make a difference and some will tell you they have run exhaustive Tests and see no difference. That is enough to confuse anyone.

I'd say it depends on how precise the Loads are, the Case size, the accuracy potential of the Rifles and the Shooter's ability are as to when you will begin to notice the groups being larger. Which also tells you nothing useful.

But, there is one convincing argument about why to do it that I keep telling myself - gaining Confidence in the Final load. I do everything I can to make all my cases as close to alike as possible(without water volume sorting) to gain confidence in them. And since Bob338 convinced me about the occasional Case creating a Flier, I look for them too.
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That said, I normally Weight Sort my cases. I do not do it to Pistol or Revolver cases or those for my 444Mar(yet).

I just picked up a Tally Sheet where I Weight Sorted some Nickle Plated 223Rem cases. There were 200 in this Lot which is below what I normally buy at one time. But the Lightest was 90.0gr and the Heaviest 92.7gr. If I remove the Lightest 11 that moves the bottom to 91.0gr and if I remove the Heaviest 11 the upper limit is 92.1gr, or 1.1gr difference for 178 cases.

Taking a quick look, there are 33 at exactly 91.4gr and 30 at 91.5gr. From there it forms the old "Bell Shaped Curve" we all learn about in our Statistics classes.

So, I use the 11 lightest and 11 heaviest to watch for Pressure Indicators and keep them separate. And I would take 9 of the 91.4gr cases and assemble them using my current most accurate Load to see how well they do and if the Seating Depth needs any adjustment. Then take another 18 from that Weight Group and load up some BBQ Loads. I use these to win my Supper from folks on occassion.

For regular Varmint Blasting, I might pick 50 cases from 91.7<->92.1gr whose weight spread is 0.4gr.
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The point being, once you have done the Weight Sort, you then know the extremes of the Lot and can break them into any size groups you want. If you don't Weight Sort, you can still cull the unexplained Fliers and it "might" do just as well. The only thing missing is the additional Confidence level of trying to make them all nearly alike.

And the farther out you shoot, the more important all the small details become.

Hey guys thanks. These are the first cases I have weighed. I did these because my local smith is putting together my first precision rifle for me. Looks like I will be using case weight to sort and case volume to define the brass I use.

think about this. The chamber volume/capacity, the area between the bolt face and the point where the bullet meets the forcing cone/rifling. If brass of a different mass/weight is placed into the chamber volume, will pressures and velocity be affected in a bench rest gun? If the chamber is less full or more full, will it make a difference?? LOL

Try this experiment!

Get about 100 trimmed and sized cases from the same lot and brand. Weigh them. Divide them into two groups. One group that is closest to uniform weight. One group that is made up of the heaviest and lightest cases (the least uniform).

Now..... reload both groups with exactly the same load and test for accuracy.

What kind of accuracy gain did you get with the cases of uniform weight?

IF there was an accuracy gain with the reloads using the cases of uniform weight, was the increase in accuracy enough to justify the time and effort you spent weighing and segregating the cases?

There is a simple way of looking at cases weight versus volume and owder capacity.

I don't weigh cases even for my BR and HBR ammo.
Here is why. Brass is 8.6 times heavier than water, and powder is average .95% of water by weight.

So lets take 5.0 gr brass weight diference. Total 5.0 gr. 5/8.6 x.95 =.55 gr of difference in powder weight. Well my scale will barely measure that. Could you tell the difference in accuracy???

Even 10gr would only change the charge weight by one grain and who knows where that extra bass weight is? 10 gr extra in the base would be different than 10 gr in the walls od the case.

quote:

Originally posted by DaMan:
Try this experiment!

Get about 100 trimmed and sized cases from the same lot and brand. Weigh them. Divide them into two groups. One group that is closest to uniform weight. One group that is made up of the heaviest and lightest cases (the least uniform).

Now..... reload both groups with exactly the same load and test for accuracy.

What kind of accuracy gain did you get with the cases of uniform weight?

IF there was an accuracy gain with the reloads using the cases of uniform weight, was the increase in accuracy enough to justify the time and effort you spent weighing and segregating the cases?

my testing showed weighing cases made groups smaller, i forget how much, but smaller. Yes worth the trouble if your want to shoot 5 shot groups under 1" @ 300 yds

Steve Ricciardelli is right about the weight of cases. I have read where cases need to be within a certian weight, etc. But I weighed all my cases once in a 30 round loading and out of a big bunch I got 30 that weighed witin 1/10 grain of each other. I weighed all my bullets until I found 30 the same weight. I even weighed the primers and weighed the powder on an electronic scale. Then I shot those rounds and then loaded up a bunch of random weights and could't see any differance except that I had spent a bunch of time weighing everything! A $3000.00 rifle might like the same weight cases a bit, but for what I shot it didn't make any differance. I even filled some cases with water writing down the CC capacity-no differance. We read about all these $3000.00 +rifles that require all this stuff and think our $375.00 Remington ADL will preform the same by weighing cases. Never seen a court case yet where a dead deer bitched about the bullet that killed him was 4 grains lighter or heavier than the rest, or that we used a Winchester case instead of alighter Federal. Sometimes we make it hard on our selves by thinking like some of the bull shit science fiction stories on tv. I thought if you did all I did man it would make a big differance! Truth is it did't help abit in 5 different rifles. I make sure the cleaned and resized cases are all trimmed the same, loaded with the same weight powder, bullets seated the same, primed the same and go for it! We need to quit thinking in rocket science terms and get back to the basics. Hey Steve I believe you know what you are talking about after the several hundred thousand rounds you have fired! I only wish I could do that!

Blob 1,

I agree (mostly) but people can go to all the trouble they want if it makes them happy.

For instance I could say you are still going to too much trouble. Could but I'm not.
But for instance, would it matter all that much if the cases wern't all exactually the same trim length. What accuracy loss would you expect if some were say 3thou shorter??
And if you happened to have some cases already primed with another brand primer, what difference then??

Lots of things probably don't matter much but we all like our little standards.
For instance I nearly fell over when I saw all these good people here standardising primer pocket holes and deburring inside 'em.
Cripes, if I can see thru 'em, that's it.
John L>

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Bench resters would eat cow turds if they thouhgt it would help.
JL.