Measuring primers

[BenPerfected]

Has anyone spent much time measuring the weight using one lot of primers with the primer weight being the only variable in the loaded round (this might be impossible with all the potential variables in the load, the wind and the shooters ability). My primer sort is to .001. I haven’t quit yet, but getting close....
This might be similar to expecting accuracy improvement useing shiney brass.....yet I still wet tumble all my brass.
My focus on perfection is mostly because of my Mother. Her saying was.....” if you aren’t going to do it right, why do it at all?
Warped in TX,
Ben

 

[Prose]

A guy named @Mulligan recently posted his results about this. If you stick to only his posts in that thread you get some good info.

 

[Mulligan]

http://forum.accurateshooter.com/th...-spread-is-acceptable-in-competition.3960990/

@BenPerfected

The link above will take you to the thread where I posted my primer tests.
CW

 

[cw308]

Way to much thinking going on for me , I uniform my primer pockets and seat to the same depth , that's about it . So many rabbit holes to go down in Precision Shooting takes the fun out of it .

 

[spclark]

A couple of seasons ago I started weighing primers (small rifle, 'Murom Plant' sourced Russian magnum, mostly KVB223M, fewer CCI BR-4 or Remington 7-1/2) just for the heck of it. I don't shoot much besides traditional Palma discipline anymore so the goal was to see whether reducing primer variation would affect scores.

I had on hand then more of the Russian SR primers than anything else as I'd preferred using them since they came onto the scene so more of them were sorted than of the others.

The end result was that weight-sorting the Russians by 0.03 grain gave me seven 'sorts' spread over a bit more than 2-1/2 grains light to heavy, the BR-4's and 7-1/2's sorted to 0.02 grains both gave three sorts spread over less than 1 grain.

Discounting other variables like wind, conditions affecting visibility with match sights (mirage, haze, smoke from wildfires, rain, snow, etc.) I felt my scores improved with less variation in elevation from using weight-sorted primers.

 

[JEFFPPC]

A couple of seasons ago I started weighing primers (small rifle, 'Murom Plant' sourced Russian magnum, mostly KVB223M, fewer CCI BR-4 or Remington 7-1/2) just for the heck of it. I don't shoot much besides traditional Palma discipline anymore so the goal was to see whether reducing primer variation would affect scores.

I had on hand then more of the Russian SR primers than anything else as I'd preferred using them since they came onto the scene so more of them were sorted than of the others.

The end result was that weight-sorting the Russians by 0.03 grain gave me seven 'sorts' spread over a bit more than 2-1/2 grains light to heavy, the BR-4's and 7-1/2's sorted to 0.02 grains both gave three sorts spread over less than 1 grain.

Discounting other variables like wind, conditions affecting visibility with match sights (mirage, haze, smoke from wildfires, rain, snow, etc.) I felt my scores improved wiless variation in elevation from using weight-sorted primers.

Speaking of discounting variables maybe we would be ahead of the game by perfecting wind reading skills rather than measuring primers. Not you in particular but all of us.

 

[PatMiles]

maybe we would be ahead of the game by perfecting wind reading skills rather than measuring primers. Not you in particular but all of us.

I resemble that remark!

 

[fyrewall]

Several years ago BTG Research produced a paper entitled something like "high speed blast waves" from a bunch of primers fired in a .308 where they actually measured the primers before and after firing to determine explosive weights. The measurements as I remember, showed the differences between brands but little difference was shown within a certain brand and type. The weights were measured with a super sensitive scale and the blast waves measured via a transducer. I forget what units were used, most likely psi.

My thoughts were the entire process was of general interest showing that most primers were very uniform but beyond that the process was sort of esoteric. I came away from reading it that the Federal 215 primer delivered the biggest blast. Surprisingly, the little CCI 450 primer was either inconsistent (bad lot?) or some test interrupt (I kept on buying and using 450's).

That paper is no longer on-line meaning that I will have to search through boxes of notes and whatever.

Some useful info shows Fed 215's and Rem 7 1/2's hottest.

Another link.

This is does not get into weighing primers but evaluates lead vs. lead free primers.

https://arxiv.org/ftp/arxiv/papers/1410/1410.6390.pdf

Considering other variables when entire completed round of ammo are tested would be variations in capacity of each case and possibly variations in neck tension. Would brass having the same preparation and even the same weight have equal capacity? Was each piece of brass for measures for velocity measured for capacity? Where barrel/chamber temperatures maintained at a constant level?

I would go for primer testing measuring blast waves vs explosive charge independent of load velocity. The old paper did this, variations in cartridge loading were not considered.

I would measure the water capacity for each piece of brass. The velocity differences are tiny, about .7 percent. The differences in the zig zag graph (speed vs. weight) might not be a factor of weight assuming speed measurements were correct. I would try for a better fit. Apparently entire primers were weighed - this assumes equal weights for cup, anvil & foil thingy.

 

[David Christian]

@Mulligan, thanks for sharing your testing results with all of us. I think it serves as a great start for this thread. A good shooting friend @Devin Wiggett and I were curious about this exact question and started our own test, yet used 20 separate pieces of prepped brass from the same lot/batch that had been previously fire formed, turned, annealed, etc. In an effort to reduce variables, all brass was prepped identically and loaded at the same time. CCI-BR2 primers. 10 on the light end (5.16 gr) and 10 on the heavy end (5.26 gr).

We developed a simple test to compare the muzzle velocity using a Magento speed, along with a dot drill alternating heavy (H) and light (L) primers. Here are the results that we came up with. What do you see in the results, or how to make this a better test?

Target impact results at 100 yards:


Here is the data:


Here is a graph of the data:


I am personally struggling to find a correlation to primer weight and either a variation of speed or a result on target. Help us make this test better. What would you change? How do you evaluate these results? Thanks

 

[dmoran]

@David Christian

Great logistics..... and Thanks for sharing them and your testing method. Good stuff !.!.!

Not to rain on your results at all, but do want to give this input:
From my own weighing and testing of primers over the years, seen some major weight variation from Lot to Lot. Poor Lot's that effected accuracy the most abrupt, typically had weight variations of at least .2-tenths of a grain or more. Myself would consider a Lot with only .1-tenth in weight variation a very good Lot, and would not expect to see much hindrances to accuracy or velocity.

Just my 2-Cents

 

[spclark]

...maybe we would be ahead of the game by perfecting wind reading skills rather than measuring primers.

Agree 100%.

Watching Kent Reeve coach or shoot supports this conclusion; I have to wonder how widespread the distribution of a particular gene he carries might be?

Something gives him an ability to see wind like no other mortal I know.

 

[Mulligan]

David,
Good stuff for sure!!!
I completely agree with Donovan.
I will also add the small differences in case volume matter a lot when we trying to separate the fly poop from the pepper.
When I performed my testing, several well respected shooters (long range bench rest, short range benchrest, and F-class) either posted to the tread or sent PM’s with advice on how to do the test. Most all of that is still in that thread (link attached above).
When I finally framed up the question the best I could, the real quesion for me was; Do the differences in primer weights effect velocity?
The answer as most assuredly, YES. The difference in primer weights is nearly all in compound, not cup and anvil.

I briefly tested this on paper, more out of curiosity than anything else.
All of my testing was with Federal 205M primers as that is what I shoot in my PPC.
I will try to dig up that one lonely group and post it.

To me, the differences in velocity were striking, especially considering in F-class and LR benchrest we often hear of the need to “weigh our powder to the kernel”.

The difference in primer weight and therefore, velocity in the brick of primers I sorted was much greater than the variation in weight you seen in your test.

I believe this sort of thing is easily lost in the noise created by the differences in the brass. I recently started a thread posing this issue, “how to best sort brass”.


Nice work!!
CW

 

[Olde Man]

Thanks Mulligan and David Christian. I tested with my labradar after reading Mulligans first post and it all points to taking 3 to 5 fps variation out of your ES. This is a very easy no brainer with my fxI120. Do 300 to 500 at a time. Now we need to identify the other 15 fps variation.

 

[Mulligan]

@David Christian,

This is the test group I referenced above.
Shot at 600 yards at the range in Whitewater, Colorado.
6 Dasher chambered by Dan Dowling, Panda F-class, Kreiger .237 4 grove 1:8, Jewel, Kebley stock, NF 15-55. JJ rest and Edgewood bags.
H4895, Berger 105 VLD’s, Federal 205M, Lapua brass.

CW

 

[dkhunt14]

@Mulligan, thanks for sharing your testing results with all of us. I think it serves as a great start for this thread. A good shooting friend @Devin Wiggett and I were curious about this exact question and started our own test, yet used 20 separate pieces of prepped brass from the same lot/batch that had been previously fire formed, turned, annealed, etc. In an effort to reduce variables, all brass was prepped identically and loaded at the same time. CCI-BR2 primers. 10 on the light end (5.16 gr) and 10 on the heavy end (5.26 gr).

We developed a simple test to compare the muzzle velocity using a Magento speed, along with a dot drill alternating heavy (H) and light (L) primers. Here are the results that we came up with. What do you see in the results, or how to make this a better test?

Target impact results at 100 yards:

View attachment 1082205
Here is the data:

View attachment 1082206
Here is a graph of the data:

View attachment 1082207
I am personally struggling to find a correlation to primer weight and either a variation of speed or a result on target. Help us make this test better. What would you change? How do you evaluate these results? Thanks

Shoot it at 1000 yards. Matt

 

[500Stroker]

Has anyone spent much time measuring the weight using one lot of primers with the primer weight being the only variable in the loaded round (this might be impossible with all the potential variables in the load, the wind and the shooters ability). My primer sort is to .001. I haven’t quit yet, but getting close....
This might be similar to expecting accuracy improvement useing shiney brass.....yet I still wet tumble all my brass.
My focus on perfection is mostly because of my Mother. Her saying was.....” if you aren’t going to do it right, why do it at all?
Warped in TX,
Ben

Just my opinion, you guys got way to much spare time on your hands.
In the past the best way I improved accuracy was trigger time at the range.
Keep up the good work.

 

[fgregorio]

The answer for your question is right there in the spreadsheet. In the sequence of shots that you fired, the mv of the light primer is always lower or equal to the mv of the heavy primer that preceded it. I have found, in my own experience that weight sorting primers by 0.02gr reduces my vertical spread, mostly past 600y.

 

[dkhunt14]

Just my opinion, you guys got way to much spare time on your hands.
In the past the best way I improved accuracy was trigger time at the range.
Keep up the good work.

Trigger time is not the fix all for BR. If you want to win consistently, you need to do alot more then just load. The competition is tight and most the others are doing it all. Matt

 

[fyrewall]

More info:

https://arxiv.org/ftp/arxiv/papers/1102/1102.1644.pdf

This paper is about actually measuring primer blast waves using a transducer.

Logically, it may or could be assumed that heavy primers of the same kind/brand that contain more explosive mix and should result in higher velocities.

Reading through this stuff I came upon: "It is clear that for many primers, sorting by mass would have the effect of reducing variations in primer strength, however, the degree of reduction this would have on muzzle velocity variations is an open question". Further on it is stated that slopes of pressure peaks are between 8/mg and 20 psi/mg. Then the authors go on to say weight measurements to get to 10 psi/mg slopes would require weighing primers within .25 and .5 mg.

1 mg = .0154 grains. They (the author(s)) go on to say this would require some pricy scale - .25 mg = .0039 grains (real light).

All this was done under controlled laboratory conditions.

My thoughts are that the loading process, including case prep, case variations, primer seating, powder weighing, powder charging, bullet seating combined with temperature variations would introduce additional variations. If possible, I would prefer to select primers having known uniform explosive charges resulting in uniform blast waves and not use velocities as a standard for primer uniformity and selection.

In addition to immediate muzzle velocities various aerodynamic factors need to be considered such as aerodynamic jump (up or down) that would occur upon driving a bullet into cross winds upon exiting the rifle barrel.

I came away from all of this with an increased appreciation of the Rem 7 1/2 primer that might provide better results in my 6.5X47 Lapua using lots of H414 on real cold days. I think I might aquire a modest stash of 7 1/2's

 

[zipollini]

I've done tons of primer sorting experiments using my analytical balance. 6XC, Norma brass, DTAC 115 RBT HBN coated bullets, H4350 powder, CCI BR-2 primers. If I prepare 20 cases exactly the same and randomly separate them into two groups of ten and in one group seat 10 unweighed CCI BR-2 primers and in the other group seat 10 weight sorted primers the lot with the sorted primers will ALWAYS produce a lower SD and ES. Always. Same for weight sorting cases. Done this same test dozens of times. Same outcome every time.