Is it a waste of time to weigh,sort) new cases?

[Goofycat]

I just weighed 500 new .221 Fireball cases and sorted them into about 15 paper bowls so as to get some idea as to how the weight varies. The weights varied from just above 82 grains down to just below 81 grains. The median was around 81.6 grains, tapering off in either direction about equally. I have not counted each bowl of cases and did not plot out a bell curve.

The Sinclair reloading and shooting handbook says, "Weighing cases is becoming more and more popular each year. Normally, we have found the weight does not vary that much within each manufactured lot. We have felt that a variance of 1.5% of case weight is a maximum acceptable limit. When selecting cases for benchrest we normally will randomly select and weigh approximately 10% of the cases. If we see a noticeable difference in the weight of these selected cases we weigh additional cases to see if there are additional cses that fall out of our limits."

Does a variance of l.5% mean l.5% from the average, the median, or from the top to the bottom of the selected case group? In the cases I weighed, there was a fairly equal count from 81.0 to 82.0 in each of the bowls,i.e.., 81.0, 81.1, 81.2, 81.3, etc), with a slight skew towards the 81.6 bowl. This gives a pretty flat bell curve.

So, which cases do I toss out, and which ones do I keep? Or do I keep nearly the whole bunch? Or do I kiss it off and shoot them all?

 

[mikecr]

I wouldn't toss em if their that close. But I'd only turn/prep the median,to save effort) at first. Then after fire forming, Check H20 capacity of them, cuz some will leave the pack here even though the cases weighed the same.

If your final load ends up fairly tolerant to case capacity or small powder variances, then you might not worry about it at all. Use em all.

 

[JER]

The variance is typically applied to the mean. If you want to apply it to the center of the sample's distribution, use the median.

 

[ReedG]

Goofy...

I spent years carefully weighing cases, sorting into batches, etc. Mostly in .223 and 6 BR but also .22-250 and .243. Then I would take the lightest batch of cases and the heaviest and load with the same load and I have never been able to see a difference on the targets at 100 and 200 yards.

I'm too clumsy to accurately use the water capacity routine. Do I fill it to the base of the neck? Top of the neck? Do I let the surface tension hold it so it actually sticks up above the neck? Whoops, now I've got a few drops on the case or on the scale. It's just not for clutzes like me.

My opinion: In a 221 you surely are not going for 1,000 shooting and I'll bet that you can never tell the difference between the weight of the cases in actually shooting unless you can do it under laboratory conditions. The wind alone will make 10 times more variation in your shooting than case weight ever could.

Unless you are trying to squeeze the last .0005" out of a group or trying for single-digit ES for 600-/1,000-yd. shooting, most of the "extreme handloading" that is discussed on this forum is not necessary. The plethora of high-quality high-tech equipment available today tends to make us all much more anal than need be. There are guys winning BR matches with some of the sloppiest loading habits I've ever seen. There are others who have figured down to how much one kernel of H4198 weighs and add two kernels to the regular load under certain conditions.

Weigh your cases if you must, but there probably isn't any definitive proof that it does or doesn't work. It's just the way we "loonies" fill in the hours instead of watching mindless TV. Remember, the next step is to weigh the bullets, weigh the primers, measure the bullets, .......... then you'll need a scale that will weigh in .00s or .000s. Lord help us .... :crazy:

 

[tenring]

I assume your .221 cases are R-P, and a one grain deviation does not seem excessive. I use Lapua brass exclusively and weigh a sample of each new box, per the Sinclair instructions. I try to stay within .1 grain for my match brass. Others go in the "culls" container. I believe other brass prep techniques are more important than sorting by weight. Some BR shooters never weigh cases.

 

[Goofycat]

Thanks for the comments, guys. I will be using the .221 Fireball cases to neck down to .20 VarTarg. The weight distribution is pretty much even across the entire spectrum of weighed cases, so I could use either the mean or median. From your comments, I don't have much to worry about if I use all the cases. The rifle,Cooper) will be used almost exclusively for ground squirrels and maybe PDs.

I would also have chosen Lapua, but they do not make .221s or .20 VTs and do not plan to,I talked to them on the phone). It's a shame. I could have purchased some Lapua .222 cases and gone through a real song and dance to neck those cases down to .20VTs, but I chose to go the easier route with the Remington cases. My wife think's I'm nuts, sitting there at the kitchen table with cases and Pact scale, plinking them one after the other into paper bowls. Maybe she's right.

Anyway, thanks for the advice.

 

[memilanuk]

In the past I weighed and sorted a batch of Lapua .308 brass,500pcs), kept 150 pcs that were all w/i 0.5gr of each other, and sold the remainder to a local hunter BR guy. Later, when those 150 were well used,20-25 firings, lost track) I went back to plain unsorted Winchester brass. No noticeable difference in chrono numbers, or accuracy,short range, I didn't shoot much long range at that point).

There is a place on the net, www.ltrdavid.net, where the fellow weighs out 500pcs, gets two nice bell curves, then water tests I think some of the heavy cases vs. the low, and plugs the numbers into Quickload. The computer says there will be 'X' amount of difference, etc. Something on the order of 3gr worth of brass weight spread = 0.5gr water capacity spread = 6" of vertical according to the computer, given the particular data that he input into the 'puter.

He shot the ammo in some F-Class matches, and it did pretty well, on call, etc. but I'm not sure he compared the come-ups from the light brass vs. the heavy brass w/ the same load, gun, scope, etc. to see if it made a noticeable difference in the real world. I'm not criticizing his methods, as he went to a lot of time and trouble to do what he did; it's just something that pops into my head as maybe something worth looking into.

Anywho, I'm weighing out 600pcs of Lapua .308 Win brass and 200pcs of Lapua 6mm BR brass this week. Figure I'll run some tests on them as I go, mainly for the sake of curiosity & killing time,waiting on the gun to get back), not that I expect to see a huge benefit. So far, 300pcs into the .308 brass I have just over a 2gr spread total...

 

[243Mendoza]

With Lapua brass, I no longer weigh brass. Many years ago, I had sorted 200 6BR brass and after 20 firings, decided that it didn't matter and put them in one batch.

 

[JER]

Unless you are trying to squeeze the last .0005" out of a group or trying for single-digit ES for 600-/1,000-yd. shooting, most of the "extreme handloading" that is discussed on this forum is not necessary.

That sums up what I think. For conventional HP and LR, an SD of 10 to 15 is good enough. I no longer bother with weighing cases.

That time is better spent shooting or snapping in.

 

[USAPatriot]

I weigh, if for no other reason than to find that one oddball case that might be dangerous. I remember 4-5 years ago seeing a pic of a cutaway case that had a big ugly lump of brass attached inside just above the webbing. That's scary. I sort to .2 or .3gr while I'm at it and leave it at that. -Rod-

 

[chino1969]

Weighing cases is something I do only for custom chambers and barrels. I personally think it's a waste of time for a factory rifle but worthwile for a custom barrel. The quality of the brass plays into the equation as well. I try to use Lapua, Norma, or Nosler custom brass where possible, and don't weigh because those brands are very consistent. For all other brands, I weigh if I want to eke out the last bit of extreme accuracy.
Chino69

 

[ronemus]

I did an experiment a couple of years ago to determine just how much effect brass weight has on .223 loads. I used WW brass,sized, trimmed and deburred, primer pockets uniformed, flash holes deburred, and neck turned), WSR primers, charges of RL-15 or N-550 powder weighed to 0.1 gr, and 75 gr A-Max bullets. Using the lightest and heaviest cases,sorted from 1000 once-fired I had on hand), I had two lots of 10 cases with a 3 gr difference in weight. The average muzzle velocity difference was 16 fps, just a bit more than the 12 fps due to 0.1 gr of powder. I choose to sort 0.5 gr lots of brass for my long range loads, but the effect will only matter at 800-1000 yards - the vertical displacement on the target from such a small velocity change is negligible at shorter distances. Unless you control all other sources of variation, the effect of brass weight is negligible.

 

[Goofycat]

Yes, I have decided not to weigh cases in the future. The extreme spread for the little .221 Fireball cases was just a little over 1 grain. The average and median values were about the same. I could do a std deviation, etc., but I plan to use all the cases for up to 250 yd varmint shooting only, so what is the point. I seriously doubt that .1 grain case weight deviation from one case to the next is going to change the fps or accuracy any meaningful amount. I do, however, want to pay attention to the accuracy of my powder measurements, since these are relatively small cases, and any sloppiness in powder weights here can cause large variances in MV/accuracy. I also plan to purchase a Sinclair concentricity gauge to check runout. Once the loads are worked up, I think I will be happy with the results.

 

[montanaearl]

mathematically, geomatrically, weight and volume are unrelated.

 

[Aussie_bob]

Well i sorted 500 6Br lapua cases by weight then necked up 100 of all the same weight to 30BR Trimed & turned the necks fireformed checked neck lengths again reweighed and decided it was a waste of time weighing before preparation and fireforming.
Even then I am still not sure its worth it but it does take out one excuse for missing that center dot or putting that 3rd shot of a perfect group just a few mm away. So what do you blame then.
The conditions and your state of mind have more effect on shooting than .3 of a grain case weight will ever have.

 

[amamnn]

I watched a raging argument, er, discussion on another forum some time back. Some folks maintained that weigh sorting only, was not a good enough guarantor of case capacity and in fact it was possible to have heavier cases with larger capacity then some lighter cases. Other folks pooh-poohed the idea. The whole thing might seem like a tempest in a teapot to hunters and plinkers, but BR shooters were very interested.

I decided to try it myself and found that the pooh-poohers were full of pooh-pooh. I did find that there was no guarantee of volume uniformity based on weight alone, and I did find several examples of heavier cases with higher volume. I measured with water in fired and FL resized, but not decapped cases which I had measured and trimmed to equal length. All shoulders were within .001" and all the heads were exactly the same. I used metric measure as 1 gram = 1 cc= 1 mL, but you can get a relative measure of volume just from weighing the water. I weighed the cases empty then filled with water so that the water was level at the top.

I've been playing around with the volume/accuracy thing ever since. So far I have fooled around with different capacity cases using the same primers and powder charges in .223 rem, 6mmppc, 30BR, and .30-06 loads. In all calibers I have tried so far it seems that I don't get any significant difference in downrange performance until the case volume is varied by 5% or more. The only way I've gotten that much difference was to neck size cases for 2 firings or more or by comparing military brass with commercial brass. Again, casual shooters will probably not need or even want to go to all that trouble to control volume when most are not even rolling cases for concentricity or culling bullets by size/weight, but it does seem to have some use for match shooting, especially at longer ranges.