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Weight sorting primers-Test

In other words this is step one down a rat hole that goes deep. I have looked for good info on ignition and as far as I can tell, it doesn’t really exist for our needs. There is a lot of hand waving, punting, and “it’s good enough”. I’m not sure it is good enough. Not when we’re try to shoot 1” groups at 1000. There’s still a lot we don’t know.

Yes - it's quite deep...in fact, it's a hole so deep and dark I suspect it might even have an event horizon LOL. Nonetheless, if a primer sorting approach proves to be of value on the target as quiet a few people have stated, there are those (including myself) willing to spend the time and effort necessary to do it. The biggest issue in this case (and others like it) is to find (or generate) sufficient experimental evidence to make an informed decision whether or not to pursue a given approach.
 
I find it odd that Courtney uses such expensive test devices, and such a half-assed scale like the VIC-123.

Having used one for a number of years for loading my match ammo, they are not the most reliable device. They use the wrong sort of tech for the application, and use software interpolation to fake being as accurate as claimed. Other areas such as EM shielding were shorted as well to meet the price point. Moving to a Sartorius GD-503 was literally a night-and-day difference.

Pretty much taints any results in that paper, as far as I'm concerned, which is unfortunate. Ten thousand dollars or so of sensors, and can't manage to use a legitimate milligram scale.
 
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I find it odd that Courtney uses such expensive test devices, and such a half-assed scale like the VIC-123.

Having used one for a number of years for loading my match ammo, they are not the most reliable device. They use the wrong sort of tech for the application, and use software interpolation to fake being as accurate as claimed. Other areas such as EM shielding were shorted as well to meet the price point.

Pretty much taints any results in that paper, as far as I'm concerned, which is unfortunate. Ten thousand dollars or so of sensors, and can't manage to use a legitimate milligram scale.
It makes me wonder if the rest of his setup was done right, to be honest.
 
Fo those not familiar with the Acculab VIC 123

https://www.affordablescales.com/acculab/vic/vic-123.asp#

Considering all the other variables involved in assembling a cartridge and then using bullet velocity to make a correlation with primer uniformity on the basis of .001 g primer weight increments seems (to me) sort of ridiculous. Going on with that, velocity changes would be expected upon actual rifle use caused by internal and external shot to shot variations.

I like the idea of evaluating primer uniformity on the basis of weight/ blast pressure and the referenced paper showing the relationship of gross primer weight vs. psi does that.

The observations in the paper regarding the inability of CCI 450's to correlate primer mass with psi would give thought to weighing an entire brick of 450's. Would this be a transitory event? Would CCI fix this or make some announcement or would CCI regard this as having no importance and recommend the use of their match primer.
 
I don't think there was anything wrong with the readout (blast pressure) Courtney used in his tests. The issue lay in his choice of a balance that couldn't accurately resolve the minute differences in primer weight necessary. Nonetheless, it can certainly be argued that using blast pressure as a readout would minimize the negative effects of other reloading variables (i.e. charge weight variance, case volume variance, neck tension, etc.) that all contribute to muzzle velocity variance, which was the main reason he adopted that approach.

One of the major issues with using total primer weight to sort primers containing different amounts of priming compound is that the priming compound itself represents a relatively small percentage of the total weight (approximately one tenth of the total weight according to Dave's data in the original post in this thread). As I mentioned previously, the total weight range for 100 Fed 205 primers I weighed on a balance capable of ~.0002 g accuracy was only .0069 g. That is not a very large spread considering that any variance in the weight of the cups and the anvils, which constitute approximately 90% of the total primer weight are included. In other posts on this topic, people have suggested that the weights of the cups and anvils are very uniform, which may be true. However, I can't imagine the variance in their weights is zero. When the overall range of total primer weights varies by only 6.9 mg (100 primers measured), which is approximately 3% of the total average weight, any contribution of weight variance by the cups and the anvils, however small, becomes an important consideration. It's all about limiting sources of error.

Likewise, the notion of using velocity as a readout for such a test may not seem to be the best approach. However, regardless of how such a primer compound weight test is carried out, ultimately, loaded rounds will be fired on the target as a means of determining whether there is a significant effect of sorting. With a well-tuned load, we can typically reduce the ES/SD values for 10-shot group to values of </= something like 10 fps/5 fps. Further, with ES/SD values in this range, the accuracy of a good chronograph has probably not yet become the limiting factor. So the use of velocity as a readout should still be within the limits of experimental error.

Put another way, if the limit of detection for average velocity is in the range of perhaps 2 to 4 fps with a good chronograph and a sufficiently large sample set, lets say 10 shots minimum, average velocity would likely not be the limiting source of experimental error. As we know, unless a shooter is willing to generate a much larger data set (i.e. 50 to 100 shots, or more), differences in average muzzle velocity in the range of 2 to 4 fps are not sufficiently large to draw valid conclusions about shot behavior on the target. We really need minimum velocity changes of 10 to 20 fps (or more) in order to conclude that velocity differences were responsible for creating a particular shot pattern (i.e. high/low) on the target, even at sufficiently long range. Again, this is all about limiting sources of error because unless the velocity differences in loaded rounds are at least 10 to 20 fps, it cannot be stated with certainty whether any shot dispersion observed was caused by velocity changes. In other words, until the estimated shot dispersion solely due to velocity becomes larger than the best actual shot dispersion produced by a given setup, velocity will not be the limiting factor in such a test.

I think that with careful attention to brass prep (i.e. case volume, neck tension, etc.) and charge weight measurement, it should be possible to use average velocity as a readout for such a primer test. After all, we're going to shoot loaded rounds anyhow, if the heaviest/lightest primers in a sample set are not capable of producing velocity changes greater that 2 to 4 fps, we could never reliably conclude that differences observed on the target were due to velocity changes, anyhow. If small changes in the amount of priming compound can produce changes in average velocity greater than the limit of a good chronograph's accuracy, then we could reliably conclude that the behavior we saw on the target was, in fact, due to a difference in the amount of priming compound and the resultant effect on velocity. As I stated above, this is certainly not the only way to carry out such a test. But for most of us, it would be the simplest way, requiring only great care in load preparation and not any specialized equipment.
 
Assuming any chronograph might have an error of .25 to .1 percent, that would result in an error for a 3000 fps load of plus or minus 7.5 fps or an extreme spread of chrony error of 15 fps for a .25 percent error chrony. Labradar says its chronographs produce .1 percent or for the same 3000 fps cartridge or a plus/minus of 3 fps or an extreme spread of 6 fps chrony velocity.

If compelled, my approach to the situation would be to weight sort primers as accurately as possible after examining unfired and spent primers. I would pry out the anvils and clean up the remnants of a moderate pile of spent primers to remove all the black crud (ultra sound) and examine each under 10X magnification and weigh the remains of each. I would then evaluate the uniformity of how the primers were seated, contact with bolt face and set-off by the firing pin - this stuff would relate to rifle and brass. I would look for any degree of primer squashing due to tight primer pockets or excessively deep seating. I would prefer to measure consistency by blast pressure and skip all the other stuff but being limited to just accuracy testing and chronograph data (no $ for pressure testing), would rely on that. I would look for erratic velocities caused by inadequate primer selection, like a standard primer selected for a huge volume case in cold temps or an excessively large & hot primer used in a tiny case. I would read my manuals. I would figure out weight stats like SD and distributions for a bunch of primers using weight data, taking into account my sample size for some confidence level. After absorbing all that good stuff I would go to my LGS and attempt to buy the same lot of primers.

Finally, I would compare my velocity spreads with group shapes. How much would a 25-35 fps velocity spread result in a up and down hit at my customary long range distances of like 600 yards as compared to unhappy node caused by any number of post primer selection efforts.

I forgot - how centered does your firing pin wack a round primer? Anvil shape?

I got to admit I screwed up when I assumed the primer weights were within .1 mg when actually they were within 1 mg. I think Dr. Courtney would cheerfully accept modification of the table where he shows .1 mg primer weights.
 
It's winter time, and I'm resurrecting this thread.....I've read this
several times and with the work done by Dave, I'm just going to
jump in with some numbers. In my wild cats I use LRP's with the
CCI BR2's being favored. I took the remaining 300 primers of my
last lot and ran them on a Peregrene scale with 2/100th's resolution.

5.14.......1
5.16.......3
5.18.....26
5.20.....38
5.22.....18
5.24.....82
5.26.....54
5.28.....61
5.30.....17

Difference of the lone 5.14 and the 5.30 is 1.6 tenth. I would think
that this spread fired together would show up on a target as a flyer
and will confirm that once the new build is done

Besides the 300 weighed, I have one more brick of BR2's but of a
different lot. I will sort these when the 300 have been put on paper.
I found a brick of standard Federal Champion LRP's that I picked up
for emergency needs. Throwing a few on the scale shows these will
be a real ugly sort. Just doing 10 had a spread of 2.1 tenths.

All in all, it only took me about an hour, 2 cups of coffee, with a
favored fusion jazz station playing in the background.
 
I have been weighing primers for 5 years now. I accepted the premise the weight difference was the compound after discussion with both Fed and CCI tech's. The year before this I had ventured a bit into the 1000 yd paper game. I was advised the ES was very important. I tested my 3 bench rifles, all 4 where in the middle to high teens. I started switching primers. I had to buy Fed 205ms because I had never used them. When I tested all 3 rifles with them I went to single diget ES. Then I decided to weigh primers really trying to fine tune my 6BRX that I shoot Varget in. Now 5 years down the road after weighing many thousands of primers I find that in any 100 pack of primers there is an average weight difference of 4 to 6 pieces of Varget. My conclusion, in I don't weigh primers non use to Debbie powder, just dump it. So I weigh every primer and sort them. No I must leave to go shoot my Springer air rifle. No reloading and no cleaning. Groups in the zeros and 1s at 25 yards.
 
I am being very simplistic here but have always wondered... if manufacturers have a process by which they can produce more consistent primers (ie BR primers) why not produce every primer you assemble in that more consistent manner? There really should be no Large Rifle BR primer. There should only be Large Rifle Primers, all of which are made the most accurate and consistent way possible. I am not a competitive shooter. I am a hunter/handloader who enjoys shooting in whatever format. I can speak for most handloaders when I say that if there is a better way to produce primers which results in more accurate loaded ammunition then use this method to produce all primers. There is no circumstance where I think to myself... I wish I had a less consistent or lower quality primer I could build some ammo with. Just thinking out loud here .
 
I am being very simplistic here but have always wondered... if manufacturers have a process by which they can produce more consistent primers (ie BR primers) why not produce every primer you assemble in that more consistent manner? There really should be no Large Rifle BR primer. There should only be Large Rifle Primers, all of which are made the most accurate and consistent way possible. I am not a competitive shooter. I am a hunter/handloader who enjoys shooting in whatever format. I can speak for most handloaders when I say that if there is a better way to produce primers which results in more accurate loaded ammunition then use this method to produce all primers. There is no circumstance where I think to myself... I wish I had a less consistent or lower quality primer I could build some ammo with. Just thinking out loud here .
Much like there are match bullets, lathe-turned bullets, and custom bullets...all of which cost more.
 
Yessir I do understand the concept of price point, options, etc... but what I've read in this thread so far suggests that there really is no physical difference in the BR vs standard primer. Maybe a visual inspection or maybe nothing at all. Possibly a guy who spreads compound more uniformly than the guy at the next bench, maybe not. So likely there really is no reason for the higher price point of a BR primer. But assuming they aren't just ripping everyone off and a BR primer is superior, who wouldn't want the superior primer? Just make those superior primers and no others. I guess if I got my wish and we had to depend on that 1 guy at Federal or CCI that's better at building primers to make every primer they sell, well then we'd never see any primers on the shelf. Oh wait...
 
Should be In grains and not grams.....And I do appreciate the graph.
"Thanks"
For practical purposes, I labeled empty trays. And not to get too anal
about it, two close sorts were mixed together and packaged. 5.28 and
5.30 went in one tray......5.26. and 5.24 went in another, and so on. I'll use
these once the build is done and work with the Mike's tuner. It's one
variable possibly out of the way, providing each cap gets busted exactly
the same way !! I won't open that can though....

Bullet sort is next. been itchin' to try that new equipment from Hollands.
 
LOL,
I just dumped your data into some of mine and caught the units and fixed them just as you were probably typing. I usually run primers on a Sartorius or a Mettler in grams, so I didn't notice yours till I looked at it again. All fixed up.
 
Yessir I do understand the concept of price point, options, etc... but what I've read in this thread so far suggests that there really is no physical difference in the BR vs standard primer. Maybe a visual inspection or maybe nothing at all. Possibly a guy who spreads compound more uniformly than the guy at the next bench, maybe not. So likely there really is no reason for the higher price point of a BR primer. But assuming they aren't just ripping everyone off and a BR primer is superior, who wouldn't want the superior primer? Just make those superior primers and no others. I guess if I got my wish and we had to depend on that 1 guy at Federal or CCI that's better at building primers to make every primer they sell, well then we'd never see any primers on the shelf. Oh wait...
Primer manufacturers say it takes more labor to obtain the consistency in the BR series. More labor => more cost.
 

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