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Primer Weight

Just adding a little context here. The primers you are weighing matter.

Some brands have processes that cause weight variance that does not correlate to differences in priming compound weight. This creates noise in any test that will frustrate an attempt to make sense of the primer weight to velocity (i.e. Fed 210M red blob).

Other brands have large variations in the weight of the metal components that frustrate attempts to identify differences in priming compound weight (i.e. Wolf KVB-7).

Other primers are really clean without those noise factors. Those primers show a definite correlation between average velocity and primer weight (i.e. CCI BR2).

HERE IS THE TRUTH:
Just because primer compound weight differences make an X difference in average velocity, that does not mean that sorting out that variation is going to reduce the ES by that amount. Instead, you will get the root-sum-square (RSS) difference in velocity variation. That variation will take extremely large sample sizes to reliably identify (think barrels not shots).

For example, on my 284, weighing primers resulted in a 12 fps difference in average velocity between the lightest and heaviest primers. ~1 to 2 fps per mg.


Based on your ES/SD to start, the difference could be almost impossible to reliably measure. Here is a process variation model (RSS) that can help to understand the implications of tolerance stacking:

ES of 20 (starting): Sqrt(20^2 - 12^2) = 16. In this case, the average ES for many, many trials would be reduced 20%. Given the general variability of tested ES values, testing by ES is at best unreliable, and at worst self-deceptive.

(Using 25% of the measured ES for assumed SD input)
SD of 5 (starting): Sqrt(5^2 - 3^2) = 4. In this case, again the SD changes 20%.

On the other hand, if your ES and SD are already this low, the question remains whether you would be better off weighing primers or learning how to shoot the rifle better?

Let's take a little different situation, that some shooters face. Will weighing primers help with my excessive ES/SD?

ES of 30: Sqrt(30^2 - 12^2) = 27.95. In this case, the ES reduced just 7.3%. While there is a reduction, it is so small that with less than huge sample sizes (200+ shots), there is a better than even chance that it will appear that the ES is worse rather than better. The answer is simply, no, it isn't the cause of your high ES.

SD of 10: Sqrt(10^2 - 3^2) = 9.53. Once again, this would be all but undetectable in any reliable way with sample sizes smaller than entire barrels worth of wasted components. Again, it isn't going to fix your high SD numbers.

In my opinion, sorting primers has a positive effect on velocity variation and vertical distribution at long range (1k yards), but that effect can only be identified through multiple seasons of shooting, not one test of 20, 40, or 100 shots.

There are lots of factors that have a much larger impact of velocity variation. Until you get to the pinnacle of good velocity variation numbers, I wouldn't bother with weighing primers, and then only to maintain an existing advantage, not to try to catch up with the shooters that are beating you match after match.
 
So If you don't sort primers and add 12fps variance, add another 12fps by not sorting by internal case capacity and lets say you add another 12fps in neck tension difference by seating bullets by "feel"..... all of a sudden you could possibly have 36fps ES in your five shot string

For all the naysayers, do you think 36fps could possibly translate to 1-2" of vertical and bigger group at 600, 1K ??

Like I said before if you are trying to shoot really small everything matters
 
So If you don't sort primers and add 12fps variance, add another 12fps by not sorting by internal case capacity and lets say you add another 12fps in neck tension difference by seating bullets by "feel"..... all of a sudden you could possibly have 36fps ES in your five shot string

For all the naysayers, do you think 36fps could possibly translate to 1-2" of vertical and bigger group at 600, 1K ??

Like I said before if you are trying to shoot really small everything matters
I don't think there can be any logical argument against your logic.
And all the plaques on your walls speak volumes to your diligence, attention to detail and hard work.
If you took your high and low single velocity of a five round string at 1000 yards and ran even a simple JBM drop chart that 36FPS is going to absolutely astound you as far as the vertical separation of those two rounds alone. My simple calculation shows just about 7" vertical dispersion "guaranteed" for that 36FPS.
Now, looking at 600 yards with the same amount of ES (low 3000FPS and high 3036) there is only 1.8" vertical dispersion. I know I would be satisfied with a match full of 1.8" groups.
But, they are all just numbers in the end. Will your group be that much bigger at 1000 yards? I seriously doubt that you will be able to tell the difference if you spend all your time weighing stuff instead of learning wind and bench manners.
Me, I was happier and had less to clutter my brain when I first started the IBS long range game and didn't have a freak'n clue what I was supposed to do.
If I "have to" do all the stuff some of you guys are to be major league I will just stay in AA ball, smile and sincerely congratulate you all for your wins.
 
Lol, thanks Jerry you're being too kind Sir :D
Talking to a lot of 600yd shooters trying to compete at a high level and win there are very few who believe all the little things will make a difference on the target and are worth their time and effort, I don't think just sorting primers is gonna shrink your groups but if you are trying to take your game to the next level it all makes difference, so is it worth going the extra mile? I can't answer that, it's definitely worth to me, your gunsmith, your equipment and bench manners must be top notch and hopefully you catch a favorable conditions to shoot small, It is very deep and twisted rabbit hole but it feels great when all the testing and other silly things we do to make match grade ammo pays off.
 
Whether weighing primers, or cases, or measuring bullet base to ogives, these are summation measurements of multiple parts of the components. Until you determine what is causing what there, you have nothing to act on.
A notion that reducing variance from these broad measurements must be beneficial -for no more than reducing variance,, is just wishful thinking.
 
Oh one more thing, I know a few top shooters who do not do any of this crazy nonsense and shoot lights out so go figure that :D
While overall I agree with you I l over whelming believe it's the Indian not the Arrow. Me, I need all the help I can get. I do all I can with the Arrow and then try not to screw it up, lol.Ki weighed primers last week. This week I started on measuring bullets .
 
Whether weighing primers, or cases, or measuring bullet base to ogives, these are summation measurements of multiple parts of the components. Until you determine what is causing what there, you have nothing to act on.
A notion that reducing variance from these broad measurements must be beneficial -for no more than reducing variance,, is just wishful thinking.
Removing the extreme outliers on either end from the equation has to improve your odds even if you are not measuring THE root of the difference. Right?
 
While overall I agree with you I l over whelming believe it's the Indian not the Arrow. Me, I need all the help I can get. I do all I can with the Arrow and then try not to screw it up, lol.I weighed primers last week. This week I started on measuring bullets .
 
Extreme outliers?
Buy good primers.
The Target is KING?
Yup. One out of group will show on the target.
Probably wasn't a bad primer.
Indian not the Arrow?
I could go on and on.
 
You guys all have valid points.
Loads, flags, setups, handling…
So much OCD goes in, to getting so little out of it all, other than a little self satisfaction.
If one can just compete against themselves, the lunacy never stops, and the groups do Shrink consistently! It’s a mind F .
The best part is the friendships you gain
 
Depending on the discipline will define the need. I shoot mostly the
short game now with a little long range sprinkled in. With the shooters
I'm around, you do not leave "anything" on the table, and quite a few
of these guy's register for the Tack Driver event every year.

Would be nice to start a poll and split it up between short range BR,
long range BR, and F-Class......
Everyone who is in doubt should test for themselves. I’m tested this on several occasions for CCI 450, 200, BR-2 and BR-4 primers. I’ve shot 10 with the lowest weight against 10 with the highest weight, I’ve fired them round robin, in individual strings back to back, and no matter what I did our chief statistician at work said there was not statistical evidence that one group out performed the other. I’ve conducted this test nothing short of 8 times using several cartridges and primers, and the results were the same every time.
Dave
 
When I've set out to test something like this I've not tried nor expected there to be a difference in group size heavy vs light. I've always looked for a poi change, at distance, when firing round robin (alternating shots in this case). Even then a condition can catch your first and/or last shot, but the groups centers either are or are not in the same location. It goes without saying you're gonna want a gun that's good enough, tuned well enough, to see the difference if there is one.

Tom
 
try minimum 20 shots with different primer manufacturers

choose one

your done

primer weight is just noise as there are too many other variables to degree the effect of small insignificant primer weight changes

look for primer defects
similar to sorting bullets you can look for the out of spec ones

the consistency of your grip to the 1 inch pound is way more important
the BREAK AWAY FRICTION in a bench gun is way more important


BUT thanks for asking now buy my book on mental shooting toughness
I never sorted primers since it's a varmint hunting rifle. But I have noticed the foil disc crinkled between some anvils, some have primer charge ozzing up around the foil edges and anvils Cu colored and some anvils stained.
 
When I've set out to test something like this I've not tried nor expected there to be a difference in group size heavy vs light. I've always looked for a poi change, at distance, when firing round robin (alternating shots in this case). Even then a condition can catch your first and/or last shot, but the groups centers either are or are not in the same location. It goes without saying you're gonna want a gun that's good enough, tuned well enough, to see the difference if there is one.

Tom
Where do you think it comes in to play for you, Tom? A gun that shoots 3” at 1000yds in a good enough place to see it?

I’ll confess to not seeing it and my best groups at 1000yds are about 3” with most of my groups more in the 5-6” range. My practice spot is an open prairie and I don’t often feel as though the conditions are steady and conducive to excellent results.
 
Where do you think it comes in to play for you, Tom? A gun that shoots 3” at 1000yds in a good enough place to see it?

I’ll confess to not seeing it and my best groups at 1000yds are about 3” with most of my groups more in the 5-6” range. My practice spot is an open prairie and I don’t often feel as though the conditions are steady and conducive to excellent results.

It's hard to say Evan, by the time you go through them to find the extremes, the work is done. And once the rifle is right, it's hard to go test something that you've already done the work....just to see if you want to undo the work if you get what I'm saying. I would think, regardless of what it is, if it shows it then it matters. And if it doesn't, then it doesn't. I found a real extreme light br2 just last weekend, I doubt I'll make a trip just to see if it goes out, as I found it and it's gone now lol. I'm just explaining how I'd try to test something that might be hard to test.

Tom
 
It's hard to say Evan, by the time you go through them to find the extremes, the work is done. And once the rifle is right, it's hard to go test something that you've already done the work....just to see if you want to undo the work if you get what I'm saying. I would think, regardless of what it is, if it shows it then it matters. And if it doesn't, then it doesn't. I found a real extreme light br2 just last weekend, I doubt I'll make a trip just to see if it goes out, as I found it and it's gone now lol. I'm just explaining how I'd try to test something that might be hard to test.

Tom
I appreciate that. Thank you. I think we all have that little war in our heads about what we think aught to do something and what actually shows up on paper. Hard to leave it be when the effect might be subtle and correlated to stronger effects that mask it. I fall in and out of the practice of sorting primers as I swing between two modes: “I am going to take out steps in the process until it falls apart to find what is actually working” and “jeez, maybe I’m leaving something on the table and need to try adding it all back in, one at a time, to see”.
 
Everyone who is in doubt should test for themselves. I’m tested this on several occasions for CCI 450, 200, BR-2 and BR-4 primers. I’ve shot 10 with the lowest weight against 10 with the highest weight, I’ve fired them round robin, in individual strings back to back, and no matter what I did our chief statistician at work said there was not statistical evidence that one group out performed the other. I’ve conducted this test nothing short of 8 times using several cartridges and primers, and the results were the same every time.
Dave
My findings are totally the opposite of yours. So yes, I do agree that
everyone should test for themselves.
 

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