Bell Curve 100 rnd lot

[Rick Ratzlaff]

I built this beautiful Bell Curve of 100 empties.
Now, how do I identify which cases fit in the individual columns? Or better put. How do you guys deal with the data to sort cases as per their data?

 

[Mg73]

Sorry for my ignorance…. I understand the bell curve concept, but what is it you have plotted here and what knowledge are you trying to glean from the data? Some clarification might be helpful. You mentioned ‘empty cases’ so I’m thinking these are measurements of cartridge cases. What do the x and y axis represent? Fired or unfired?

 

[Rick Ratzlaff]

Their empty cases. And the distribution of pieces. Brass, projectiles are sorted by different parameters. I get that. The Bell Curve identifies how many cases in each sort or column. But how does one identify which case fits in each column?

 

[Jeff Porter]

You have a histogram of the number of cases of each bucket in the bar graph. The curve shows the smoothed distribution. You have 80 pieces in the four largest buckets. The 20 out side those - you have to decide what your acceptance criteria is.

 

[fkimble@charter.net]

Tell us what you measured so we at least have a clue what the numbers mean!

Frank

 

[Bill Norris]

Their empty cases. And the distribution of pieces. Brass, projectiles are sorted by different parameters. I get that. The Bell Curve identifies how many cases in each sort or column. But how does one identify which case fits in each column?

So have you sorted by weight here? Got to give us more info and exactly what you are asking us for.

 

[Bill Norris]

Those 80 pcs. Jeff pointed out would normally be used as the load development and the other 20 would normally be used as sighters or foulers.

 

[TonyinKY]

I buy Lapua brass for my match rifles. I’ve always sorted by weight. When I reload for a 6PPC at the range I usually get about three different 25 count “batches” out of 100 that will weigh within a few .10 of a grain and that will shoot a barrel out.

To go preloaded for my 30BR for enough to shoot 3 yardages I start with 300 pcs and usually get about 270 pcs that are within 1.5 gr spread. Here are results from the last 300 batch:

 

[jelenko]

Their empty cases. And the distribution of pieces. Brass, projectiles are sorted by different parameters. I get that. The Bell Curve identifies how many cases in each sort or column. But how does one identify which case fits in each column?

You have to identify each case as you measure it.
If you didn't sort the cases by the variable you measured you have to go back and measure each one again.

 

[Rick Ratzlaff]

Ya that's what I kind of suspected. One can use the "Bell Curve" for various examinations. So I'm just trying to learn the process to go from this point in data results to sorting criteria. I would like thee data to be live and Bill Gates tell me each time I enter the data the decision is made and the spread sheet tells me which sort group it fits into. That's what computers were made for. I thot. We did cattle that way, but each had an ear tag or an ID.

 

[K22]

In an interview with Eric Cortina, a Hall of Fame Benchrest shooter, Neary (can't remember his exact name or spelling), said he stop weighing and sorting cases by weight. He gave some very compelling technical reasons why it contributes nothing to accuracy.

Maybe some of you members that are high tech can upload the video and post on here in the hopes it may prevent some poor soul from going down the rabbit hole of weighing and sorting cases.

 

[Bill Norris]

In an interview with Eric Cortina, a Hall of Fame Benchrest shooter, Neary (can't remember his exact name or spelling), said he stop weighing and sorting cases by weight. He gave some very compelling technical reasons why it contributes nothing to accuracy.

Maybe some of you members that are high tech can upload the video and post on here in the hopes it may prevent some poor soul from going down the rabbit hole of weighing and sorting cases.

I believe this is the one you are referring to.

 

[Bill Norris]

Or this one. Both are very good videos and Jack also has about 10 different short videos (short classes) concerning load development and the Short Range shooting.

 

[ELR LVR]

In an interview with Eric Cortina, a Hall of Fame Benchrest shooter, Neary (can't remember his exact name or spelling), said he stop weighing and sorting cases by weight. He gave some very compelling technical reasons why it contributes nothing to accuracy.

Maybe some of you members that are high tech can upload the video and post on here in the hopes it may prevent some poor soul from going down the rabbit hole of weighing and sorting cases.

When weight sorting my 22 BR brass
I shot some test groups that were within 4 Grains
126-130 grns
a 3% difference in weight
Shot as small of groups as anything (0.136")
However , I figure there must be a percentage out that WILL make a difference
I have weighed same headstamp 284 brass and found an occasional Heavy weighing as much as 10 grains more than the rest
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If you meter out 10 grains of brass shavings....thats quite a bit of brass to decrease internal volume which has got to make "Some" kind of difference in pressures,
same as seating a bullet deeper a certain amount
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And when going toward Max load side of the spectrum , makes me nervous not to weigh
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It may not make much difference if using medium (not Hot) loads

 

[dgeesaman]

Assuming you didn't find any truly defective outliers, take your five highest and five lowest cases. Now load the ten from the very middle.

Now shoot your best load in the best conditions and see if you can show any difference at all on target. Most of the time it doesn't make any difference.

Then stop sorting or don't stop sorting. Some shooters want to eliminate every conceivable variable, regardless of actual significance. Others focus their effort on variables that have shown some indication of significance. I'm in the latter category but I don't compete. Benchrest competitors often take the first approach.

 

[markm87]

Their empty cases.

I hope your Grammatical skills don't reflect your Stats skills.

 

[K22]

I believe this is the one you are referring to.

Yes, about 17:30 in, he discusses weighing cases and the reason it does not affect accuracy. Thanks for posting.

 

[ronemus]

Assuming you didn't find any truly defective outliers, take your five highest and five lowest cases. Now load the ten from the very middle.

Now shoot your best load in the best conditions and see if you can show any difference at all on target. Most of the time it doesn't make any difference.

Then stop sorting or don't stop sorting. Some shooters want to eliminate every conceivable variable, regardless of actual significance. Others focus their effort on variables that have shown some indication of significance. I'm in the latter category but I don't compete. Benchrest competitors often take the first approach.

I did an experiment several 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 .223 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. I also shoot .284, and because the brass is twice as heavy I batch in 1 gr lots.

 

[Ranger188]

I asked a hall of fame shooter that everyone here knows how he sorted brass.
Said he sorts by how it shoots..
He knows his load and when one doesn't do what it should he'll sort it out
and gives it another try. If it fails then gets cut from the competition loads.
You can't tell by looking at it. But you can tell by how it actually shoots.
That's what matters.
Makes a lot of sense.

 

[TTE]

In my pea brain, I would think the only way to accurately separate cases would be to use water in each case and weigh the water that comes out of each case.

However, I don't know nothin' about nothin' ... I'm a hunting rifle shooter