Vertical Dispersion - Weighing Primers
- Thread starter MikeMcCasland
- Start date
According to the data in the Coutney military report referenced above, there may indeed be an advantage present for those that can sort to the quarter or half of a milligram (see source below):
Furthermore, his data shows that the peak blast pressure (psi) vs. primer total mass (mg) regression line has a correlation coefficient (R) for the CCI 450 primers of 0.03, which is ridiculously low and as good as saying there is virtually ZERO correlation between the peak blast pressure and the mass of the CCI 450 primers. So if you are using CCI 450’s, like I am, sorting shows zero benefit.
In any case, I will be sorting primers for my 3x600 F class match next weekend. Typically, in my 600 yard competitions, I’m seeing between .3 to .5 vertical moa (based on measured targets). I’ll report back.
Dave
Furthermore, his data shows that the peak blast pressure (psi) vs. primer total mass (mg) regression line has a correlation coefficient (R) for the CCI 450 primers of 0.03, which is ridiculously low and as good as saying there is virtually ZERO correlation between the peak blast pressure and the mass of the CCI 450 primers. So if you are using CCI 450’s, like I am, sorting shows zero benefit.
In any case, I will be sorting primers for my 3x600 F class match next weekend. Typically, in my 600 yard competitions, I’m seeing between .3 to .5 vertical moa (based on measured targets). I’ll report back.
Dave
@Dave M.
Sort until you have an obvious normal distribution of weights.
Take 10 low outliers and 10 high outliers, and the rest from NEAR the mean.
If outliers weighed to the nearest milligram don't show any benefit, weighing to 0.1mg surely won't.
Load your 70 or so rounds for your 600X3 isolating the ten low and 10 high for your second relay.
Ex: Sighters from mean weight, relay one from mean weight, first 10 of relay 2 low outliers, second 10 of relay 2 the high outliers. Shoot relay 3 from the mean weight primers.
All same day, almost the same environment, same reloading batch, same you
Post scores.
One hint for those without a precision lab balance, or just to save a few seconds per primer:
Tare the scale then add a 1 gram check weight to the scale.
Will indicate 1.000g without a primer and 1.350g (or so) with a primer.
Milligram resolution should show outliers. With a milligram indicating scale the +/- half count rollover will be hidden. Range of weight, high to low should be a FEW milligrams. You are only looking for outliers.
With a 1g base, DRIFT and REPEATABILITY will be instantly visible.
Auto zero of balance won't be triggered. At a very small measuring range (light to heavy primer) scale LINEARITY will NOT be a factor. Full scale calibration, percentage based, will NOT be a factor except in the WORST conditions. The 1.000g will monitor every weight performed. If it drifts, remove the check weight, tare, add the check weight.
This 1.000g check weight is a continuous IN PROCESS check.
If you don't trust the process, reweigh the lowest and heaviest outlier after sorting.
Red and green markers in the case groove to track outliers in case you spill the box
Sort until you have an obvious normal distribution of weights.
Take 10 low outliers and 10 high outliers, and the rest from NEAR the mean.
If outliers weighed to the nearest milligram don't show any benefit, weighing to 0.1mg surely won't.
Load your 70 or so rounds for your 600X3 isolating the ten low and 10 high for your second relay.
Ex: Sighters from mean weight, relay one from mean weight, first 10 of relay 2 low outliers, second 10 of relay 2 the high outliers. Shoot relay 3 from the mean weight primers.
All same day, almost the same environment, same reloading batch, same you
Post scores.
One hint for those without a precision lab balance, or just to save a few seconds per primer:
Tare the scale then add a 1 gram check weight to the scale.
Will indicate 1.000g without a primer and 1.350g (or so) with a primer.
Milligram resolution should show outliers. With a milligram indicating scale the +/- half count rollover will be hidden. Range of weight, high to low should be a FEW milligrams. You are only looking for outliers.
With a 1g base, DRIFT and REPEATABILITY will be instantly visible.
Auto zero of balance won't be triggered. At a very small measuring range (light to heavy primer) scale LINEARITY will NOT be a factor. Full scale calibration, percentage based, will NOT be a factor except in the WORST conditions. The 1.000g will monitor every weight performed. If it drifts, remove the check weight, tare, add the check weight.
This 1.000g check weight is a continuous IN PROCESS check.
If you don't trust the process, reweigh the lowest and heaviest outlier after sorting.
Red and green markers in the case groove to track outliers in case you spill the box
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I like the process. It is a little different than my process was going to be, but I can certainly see the value in your process. I’ll let you know what happens (if I shoot). My ex has Covid so I’m keeping my son away from her until she is recovered. Hopefully by Saturday next week she will be in the clear (just tested positive this morning).@Dave M.
Sort until you have an obvious normal distribution of weights.
Take 10 low outliers and 10 high outliers, and the rest from NEAR the mean.
If outliers weighed to the nearest milligram don't show any benefit, weighing to 0.1mg surely won't.
Load your 70 or so rounds for your 600X3 isolating the ten low and 10 high for your second relay.
Ex: Sighters from mean weight, relay one from mean weight, first 10 of relay 2 low outliers, second 10 of relay 2 the high outliers. Shoot relay 3 from the mean weight primers.
All same day, almost the same environment, same reloading batch, same you
Post scores.
One hint for those without a precision lab balance, or just to save a few seconds per primer:
Tare the scale then add a 1 gram check weight to the scale.
Will indicate 1.000g without a primer and 1.350g (or so) with a primer.
Milligram resolution should show outliers. With a 1g base, DRIFT and REPEATABILITY will be instantly visible.
Auto zero of balance won't be triggered. At a very small measuring range (light to heavy primer) scale LINEARITY will NOT be a factor. Full scale calibration, percentage based, will NOT be a factor except in the WORST conditions. The 1.000g will monitor every weight performed. If it drifts, remove the check weight, tare, add the check weight.
This 1.000g check weight is a continuous IN PROCESS check.
If you don't trust the process, reweigh the lowest and heaviest outlier after sorting.
Red and green markers in the case groove to track outliers in case you spill the box
dave
Wishing you and the Ex the best.
I don't get many opportunities to just test loads @ 600 so I slip in a 10 or 20 round string in the middle of the 60.
I now weight my powder charges in grams with a 10.000g Continuous In process Check weight.
I don't get many opportunities to just test loads @ 600 so I slip in a 10 or 20 round string in the middle of the 60.
I now weight my powder charges in grams with a 10.000g Continuous In process Check weight.
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I don't weight primers, and all those who do, go on and continue doing so.
But it seems that you're weighing variables, that you have no control over...there are primer cup weights variations, primer mixture weights and consistency variations, and primer anvil weights variations, each one a variable, and inconsistent to the next... so you're not just measuring the amount of primer mixture.. and its active ingredients...and the active ingredients in the mixture are constantly varying from primer to primer...So you have no idea of what the total weight is actually measuring. Unless you assembled the primers yourself...and separately weigh each component to your tolerance then assembled them, you'd have an idea of what you're measuring, but there will still be variations, however so small as your tolerances allow then there is the mixture variation, not only weight but chemical composition, in total molecular consistency.
So, I see it as fruitless endeavor for me...but it might help you, if primer assembly weights vary widely in your batch of primers, for a physical or mental edge, ...if it just makes you feel better...weigh away.
But it seems that you're weighing variables, that you have no control over...there are primer cup weights variations, primer mixture weights and consistency variations, and primer anvil weights variations, each one a variable, and inconsistent to the next... so you're not just measuring the amount of primer mixture.. and its active ingredients...and the active ingredients in the mixture are constantly varying from primer to primer...So you have no idea of what the total weight is actually measuring. Unless you assembled the primers yourself...and separately weigh each component to your tolerance then assembled them, you'd have an idea of what you're measuring, but there will still be variations, however so small as your tolerances allow then there is the mixture variation, not only weight but chemical composition, in total molecular consistency.
So, I see it as fruitless endeavor for me...but it might help you, if primer assembly weights vary widely in your batch of primers, for a physical or mental edge, ...if it just makes you feel better...weigh away.
I'll will have to scan back and find that report that shows almost no pressure to mass correlation with CCI 450 primers. Just seems strange for one type of primer tested when all others had a much higher psi/mg slope.
"
"
Mulligan
Silver $$ Contributor
Jim,
I have used both, grains is an easier unit of measure for me think about…ponder. My scale is more comfy with grams. I believe the scale is a touch more precise when viewing the results in grams vs grains. Therefore, I now mostly use grams.
CW
edited to include link to the original thread with lots of colorful opinions.
How much "Extreme Spread" is acceptable in competition?
A little background, This is in regards to a thread I read on this forum regarding weight sorting primers. I have attached a short article describing a quick test I performed to see if a real test is warranted. In the attached "quick test"- The average MV from the lightest 5 primers (actually...
forum.accurateshooter.com
@Dave M.
Sort until you have an obvious normal distribution of weights.
Take 10 low outliers and 10 high outliers, and the rest from NEAR the mean.
If outliers weighed to the nearest milligram don't show any benefit, weighing to 0.1mg surely won't.
Load your 70 or so rounds for your 600X3 isolating the ten low and 10 high for your second relay.
Ex: Sighters from mean weight, relay one from mean weight, first 10 of relay 2 low outliers, second 10 of relay 2 the high outliers. Shoot relay 3 from the mean weight primers.
All same day, almost the same environment, same reloading batch, same you
Post scores.
One hint for those without a precision lab balance, or just to save a few seconds per primer:
Tare the scale then add a 1 gram check weight to the scale.
Will indicate 1.000g without a primer and 1.350g (or so) with a primer.
Milligram resolution should show outliers. With a milligram indicating scale the +/- half count rollover will be hidden. Range of weight, high to low should be a FEW milligrams. You are only looking for outliers.
With a 1g base, DRIFT and REPEATABILITY will be instantly visible.
Auto zero of balance won't be triggered. At a very small measuring range (light to heavy primer) scale LINEARITY will NOT be a factor. Full scale calibration, percentage based, will NOT be a factor except in the WORST conditions. The 1.000g will monitor every weight performed. If it drifts, remove the check weight, tare, add the check weight.
This 1.000g check weight is a continuous IN PROCESS check.
If you don't trust the process, reweigh the lowest and heaviest outlier after sorting.
Red and green markers in the case groove to track outliers in case you spill the box
You Sir, are a man that has made being OCD an advantageous character trait.
CharlieNC
Gold $$ Contributor
Depends on the degree of weight variability, was this just a uniform lot? Are all of these just a snapshot at a point in time? These results are convincing that weight matters, but far from characterizing which brand is best over the long haul.
To accompany my gram weighed primers I have lightly cleaned the primer pockets with my 21st century micro adjust uniformer set at just shy of .127, then seat the .122 primer at .009 below flush using a micro click adjustable 21st century hand primer I can get a repeatable .004 crush, with a witness mark on the seater I can test plus or minus / better or worse with results printed on paper at 500 yards, all in my effort to clean up my ignition a bit and hopefully trim my 1 k aggs.
I may not see a difference but at least I have assigned a number to the process .
I may not see a difference but at least I have assigned a number to the process .
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Doesn’t work with an autothrow system though, correct?
@Dave M.
I don't have an autothrow system.
Might be able to fudge target charge.
Zero, add check weight, charge to a total that is charge Plus check weight??
If you trust your weighing equipment then extra monitoring isn't needed but I still read threads about weighing problems with drift or static being issues with accuracy even with really good systems.
I downloaded the pdf of the primer test.
I'm a run of the mill F-Class shooter still trying to Master 600 before moving on to 1000.
My equipment is only capable of beating me. That's the goal. Do better next time.
Won't win but it's gonna be a long ride home if a 22N in F-Open beat you
The closest 600/1000 meet is on the last Saturday of the month. Looks like April.
The wife and I need a couple trigger sessions at a closer 100yd range before then.
I don't have an autothrow system.
Might be able to fudge target charge.
Zero, add check weight, charge to a total that is charge Plus check weight??
If you trust your weighing equipment then extra monitoring isn't needed but I still read threads about weighing problems with drift or static being issues with accuracy even with really good systems.
I downloaded the pdf of the primer test.
I'm a run of the mill F-Class shooter still trying to Master 600 before moving on to 1000.
My equipment is only capable of beating me. That's the goal. Do better next time.
Won't win but it's gonna be a long ride home if a 22N in F-Open beat you
The closest 600/1000 meet is on the last Saturday of the month. Looks like April.
The wife and I need a couple trigger sessions at a closer 100yd range before then.
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Never weighed primers. However I noticed if you look at the anvil side on some primers you can see the charging compound ozing out around the foil. Don't remember which brands but some anvils have stains on them and others are clean.Hey Guys,
I'm not looking to start a debate on the merits of weighing primers, or if it's worth the time investment. I've already decided to give it whirl, and I've weighed out 1,000 of them into groups separated by .02gr mostly (with some extreme outliers culled entirely).
I will say I was pretty surprised by a couple of observations. First, there was way more variation than I was expecting to find. I had a range from 2.28gr all the way up to 2.52gr. Most fell right around 2.40-2.46gr; nice little bell-curve.
It's not my intent to mix any weight groups; just going to load all those that weighed the same together.
That said, I'm not going to get a chance to shoot these until my next match, but as of late I've been struggling a bit with vertical in my load. It'll hold 10-ring vertical consistently at 1,000, but it's not as good as I see from some of the top guys.
I've played around with depth in .002 graduations, but can't seem to tune it any tighter, so here we are. I think my powder node is on point as I'm in the usual velocity range for my barrel length/bullet combo, and generally speaking the gun is shooting quite well.
My question: To those that have weight sorted primers, how much (if any) improvement in vertical did you see?
Bring on the discussion; my body is ready.
Components:
200.20X
N150
Lapua Plama - turned .014"
CCI 400s
.0015 'interference fit'
AMPed every firing
If I’m reading you correctly;
What you’re saying is to run an abbreviated ladder with each primer to determine which your set up prefers and most guys do that..whereas the test I’m looking at is the effect of weight sorted and depth on a tuned load and in my recent tests I have not seen any negative effects only minimum vertical dispersion
Ray
I really can’t find a downside to sorting a few primers, if you don’t them no one will know except yourself but hey it can’t hurt ya to give it a try.
Jim
I shot this morning in a 600 yard competition. It was only two 20 round strings, so I had to change my approach for the experiment.
I’m shooting a 6 dasher with 1945 rounds on the barrel. 33.1g RL-15 with Berger 105g VLD Targets, CCI 450 primers, 3080fps MV, shooting .009” into the lands.
in Round 1, I used only primers from the same lot that had a mass of .237 grams (the median of 300 primers measured). All shots, including sighters, were from the .237 grams sorted group.
In round 2, I used 10 primers from the light end of the distribution (all had a mass of .233 or .234 grams) and 10 primers from the heavy end (all weighed .240 grams). I mixed up the high and low primer rounds in my 20 shots for record so I wouldn’t skew the data by knowing which were high or low mass primer rounds.
Round 1:
Light rain, 29.88” station pressure
Wind 5-9mph from 2-4 o’clock
200-13X
Vertical - 3.553” (0.566 moa)
Horizontal - 3.555” (0.566 moa)
Round 2:
Light rain, 29.882” station pressure
Wind 6-10mph from 1-4 o’clock
200-17X
Vertical - 1.707” (0.272 moa)
Horizontal - 4.850” (0.772 moa)
Oddly, the group with less vertical was shot with primers at opposite tails of the distribution. I guess weighing primers has very little effect. I can’t see any value in weighing CCI 450 primers. This is the same conclusion the authors of the previously referenced military article came to regarding #450 primers. Zero correlation.
The wind was a little more switchy in round 2 and that’s what I’d attribute the wider horizontal variance.
Note that in Round 1, all shots (including 13 sighters/foulers) has primers weighing .237 grams. The average velocity at the target was 1979fps with a 16.6fps SD.
In Round 2, shot with both high and low mass primers, had the exact same velocity at the target but only a 10.2fps SD
target pics:
Round 1:
Round 2 target pics:
Needless to say, I don’t see primer weighing or sorting in my future. Feel free to critique or ask questions.
Interesting study and I’m glad I did it. I suspect the results could be much different using other primer brands or models.
YMMV,
Dave M.
I’m shooting a 6 dasher with 1945 rounds on the barrel. 33.1g RL-15 with Berger 105g VLD Targets, CCI 450 primers, 3080fps MV, shooting .009” into the lands.
in Round 1, I used only primers from the same lot that had a mass of .237 grams (the median of 300 primers measured). All shots, including sighters, were from the .237 grams sorted group.
In round 2, I used 10 primers from the light end of the distribution (all had a mass of .233 or .234 grams) and 10 primers from the heavy end (all weighed .240 grams). I mixed up the high and low primer rounds in my 20 shots for record so I wouldn’t skew the data by knowing which were high or low mass primer rounds.
Round 1:
Light rain, 29.88” station pressure
Wind 5-9mph from 2-4 o’clock
200-13X
Vertical - 3.553” (0.566 moa)
Horizontal - 3.555” (0.566 moa)
Round 2:
Light rain, 29.882” station pressure
Wind 6-10mph from 1-4 o’clock
200-17X
Vertical - 1.707” (0.272 moa)
Horizontal - 4.850” (0.772 moa)
Oddly, the group with less vertical was shot with primers at opposite tails of the distribution. I guess weighing primers has very little effect. I can’t see any value in weighing CCI 450 primers. This is the same conclusion the authors of the previously referenced military article came to regarding #450 primers. Zero correlation.
The wind was a little more switchy in round 2 and that’s what I’d attribute the wider horizontal variance.
Note that in Round 1, all shots (including 13 sighters/foulers) has primers weighing .237 grams. The average velocity at the target was 1979fps with a 16.6fps SD.
In Round 2, shot with both high and low mass primers, had the exact same velocity at the target but only a 10.2fps SD
target pics:
Round 1:
Round 2 target pics:
Needless to say, I don’t see primer weighing or sorting in my future. Feel free to critique or ask questions.
Interesting study and I’m glad I did it. I suspect the results could be much different using other primer brands or models.
YMMV,
Dave M.
RegionRat
Gold $$ Contributor
@Dave M. any idea of the year or batch of your primers, and if you have the actual stats on the weights would you mind sharing them? N, Avg, StDev?
Sometimes, the humans, tooling, and QC involved in making primers allow escapes. As much as I do not wish to see it again, there have been some from every brand over the years.
Nice shooting.
Sometimes, the humans, tooling, and QC involved in making primers allow escapes. As much as I do not wish to see it again, there have been some from every brand over the years.
Nice shooting.
I didn’t enter them all into excel but feel free to do so from my crude graph of 300 primers sorted by mass. I suspect with 123 of them having a mass of .237 grams and almost as many pieces under that mass as there were over, that the average would be darn close to .237. It seemed very close to normally distributed.
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