Weight sorting primers to improve SD

[RAVEN]

His and Julie's guns were one of the top scorers over there! So there has to be just more to it than jamming a primer up butt of a case

Yes, that’s right Plumbs Neck tension /powder charge/bearing surface/meplating/pointing/barrel cleaning/firing pin & spring functionality etc. etc.

Some advice Plumb7
chronys don't win events accurate loads combined with good rifle handling and rest setup and of course wind reading. Focus on a few of those things first you will get far greater return than weight sorting primers.

RB

[plumbs7]

Some advice Plumb7
chronys don't win events accurate loads combined with good rifle handling and rest setup and of course wind reading. Focus on a few of those things first you will get far greater return than weight sorting primers.


Thanks Ray for the advice ! I'll keep focusing on the above as always ! Incidentally, it only took me about 10 minutes to weigh 90 primers into 35 grams and 36 gram lots ! This is as per everything in open experimentation so yep it may not work . But let's see if it works ? It's just 10 mins of my time ?

Anyway ! All good ! See ya on the mound !
Graham Sells Dalby / Tara RC

[ecomeat]

! Incidentally, it only took me about 10 minutes to weigh 90 primers into 35 grams and 36 gram lots ! This is as per everything in open experimentation so yep it may not work . But let's see if it works ? It's just 10 mins of my time ?

I do weight sort primers for Queens and some OPM, batching them in lots to 0.001 gram and I did read that article quoting Bryan Litz as saying that you can halve your SD by weighing and batching to 0.001 gram.
It seems you have only batched yours to 0.010 gram...not to 0.001 gram...possibly relying on your Chargemaster scale which simply doesnt have the necessary resolution (and isn't accurate enough)
Typical Federal 210 GM large rifle primers weigh from 0.351gram to 0.363 gram,(that was what the last few hundred that I batched weighed in at, anyway) and to achieve the return on your time that Litz is talking about (ie a measured effect on your SD) you have to batch 0.351, 0.352, 0.353 etc. Unfortunately you have only batched to 0.35gram, and 0.36 gram so while it can't do you any harm it's also highly unlikely to have any measurable effect
Where you have just one batch at 0.35 grams, Litz (and me too ) would have ten , from 0.350 gram, up to 0.359 grams.

[Razer]

I firmly believe in the try and prove method.
The easiest way to achieve this is when you shoot an X is to put the case in a seperate box. On decapping you put the primer in a special container marked 'For Queens only'.
I save all my proven primers ready to export to Ireland along with my tested proven to work matches.

[Tim N]

Do I detect a note of sarcasm??
Apparently the lowest form of wit(that's why I can spot it so easily).

So is there any serious testing that has been documented?

[johnk]

German Salazar was once considered to be the expert on primer matters & had well documented experiments ha had carried out, the distillation of which was, "Use the least aggressive primer necessary to light the charge." Unfortunately, within the last year or so, he went in another direction & dismantled his web site.

You may have seen his photos of the relative flame generated from primer type to primer type. Unfortunately, it's all now just a memory.

[RAVEN]

Yes, I remember it well John
and the other interesting thing was that Magnum primers don't necessarily mean higher energy flame sometime just a thicker cup
any way back to weighing may primers
RB

[williada]

I am really quite entertained by the banter. Many of us take shortcuts because it must work because that bloke says it does its good enough for me. The only way you can be sure is to test it for yourself or you know that bloke has tested it with scientific methodology and the results can be verified independently.

If someone like Cam assisted someone for good reason, I would be inclined to listen because he's probably right.

Let’s explore the logic and the actual.

1. Can a difference between primer weights be measured accurately? Yes, on A&D like scales.
2. What causes the differences? Metal cup stampings are fairly consistent and less likely to alter volume due to temperature changes affecting the die as compared to injected liquid of explosive which dries during manufacture. The hot gas and the incandescent particles which light the powder charge vary. As such they have a different effect on accuracy and pressure.
3. Do primer manufacturers measure brisance? Yes they do, by sample test batching of a different section of a manufacturing run. A few years back we got crook barrel steel and when suppliers were questioned we were told the steel we got came from the outside of crucible rather than the core. The mix of elements was different.
4. What do manufacturers do with different batches? They differentiate by top or standard etc. As do rimfire ammunition manufacturers using sample batches.
5. How come I can’t tell the difference between the performances of the labels sometimes? Because most of the time there is no difference if the whole run is within performance indicators. Respective boxes are labelled just to meet orders.
6. Can the sampling methods guarantee that thousands of primers manufactured are representative of the sample? No. Because if you weigh them, you will see differences by batching the differences and testing for standard deviations of projectile velocity. You must have a minimum sample size of 30 to be statistically significant. Of course hundreds verify the results.
7. Do the variances matter? That depends on what personality your barrel has. We have got used to high standards from the manufacturers. It doesn’t matter if your barrel compensates unless in the remote case a brand change coughs one well ouside compensation paremeters. It will matter if your barrel has a neutral lift profile and uses a nodal or an OCW tune at 1000 yards because weak primers drop velocities and you will fall out at 6 o’clock. By adjusting for this it can appear you have vertical problems. But you can counter that with a low SD.
8. By the way, how many times do you shoot 1000 yards? Stuff all.
9. Will it matter for super centre count? As much as a low SD will.
10. So it’s important then to batch primers by weight? Your call. I want to beat you if I have time to do all this stuff.
11. If I haven’t got time to do that should I test different brands from different manufacturers? Absolutely, it’s critical to match the powder before you start full load development.

[dave]

when weighing cases, due to variations in the thickness of the rims and or extractor groove, cases of identical interior volume, can and do weigh significantly differently.

in regard to weighing primers, is it assumed that the cup and anvil are all equal in weight?

otherwise, weight variations might not be due to just primer compound variations.

cheers
dave

[williada]

Dave, most of the variance does come from the compound, because if you think about the analogy you made with cases, they are subject to about 10-12 drawings and multiple heat treatments which makes them harder and softer and not all identical. So when they are drawn wall sizes etc vary. If you think about how a cup and anvil are made, they are pressed in one hit so that reduced the amount of variance once machines are at operating temperature, is negligible. So the likelihood that that is the problem is not as great as the compound. Sure changes in dies can make things different between batches.

[johnk]

What about the Federals with that splash of red wax?

[williada]

Good point John, another variable if you like the wax treatment. Might be colour co-ordinated with red toenails.

[dave]

williada

I appreciate your comments and input, but J4 and sierra jackets are I assume stamped (to the highest standards) in 1 pass and from batch to batch and within batches there are discernable weight differences.

also the actual degree of accuracy of the scales being used for any comparisons need to be taken into consideration.

I am not aware of it, but perhaps some keen benchrester has been motivated to carefully disassemble, analyse and chart the weights of the primer components.

perhaps, it is just an advertising claim, but Remington claims that “individual primer pellet weight is controlled to 0.1 grams" (0.1543 grains).

I would be interested to know, what percentage of actual primer compound weight, the .15 grain variation is, and what effect on velocity that the same primer compound variation would have.


cheers
dave

[Barry Davies]

I weigh my primers.
I use Federal 210 in Jennifer's Rifles.
Some years ago ( when I had unhindered access to facilities ) I did many tests on the 210 primers over a considerable amount of time and number of shots --considerable.
Without going into the the finer details 0f procedure my findings are as follows.

Primer cups including anvils and less crud are consistently within 0.02 gns

Primer weight variation was 0.28 gns ( this is solely compound )

Speed variation over the 0.28 gns variation was in the region of 33 FPS -- observed after many 100's of rounds, many varied conditions, and many variations of the same projectile ( Sierra 2155 )

Add this speed variation to the normal variation you get because of those multitude of other variations and suddenly you have some accountability for those sometime large groups.
Now, that was for the old red boxed 210's. The new blue boxed 210's only have half the variation -- 0.14 gns
I offer this for what it's worth and you can make you own decision as to weighing.
I still weigh my primers and batch them into 0.04 gn lots.
Barry

[williada]

Dave its hard to pin it all down. The only bloke I would trust to give you that information is Barry Davies. We can modify the effect of variance with a positively compensating barrel or a barrel tuner. In the case of a neutral barrel profile and a negatively compensating rifle the variable primer comes into play at 1000 yards where things are marginal.

The other thing that has been done with primers at Aberdeen proving grounds in the States with primer testing is they reported the effect is worse on slower burning powders as they did tests showing the change in the pressure curve, from memory.

Whatever causes the variance in weight there is a correlation with SD's and Cam noted that as did a few others.

A few years back we had problems with bullets not coming from the same machine yet put into the packets. The same thing may apply to jackets, as well as die wear issues unless you make your own bullets and the jackets are a separate issue. But in that case the jackets are lubed as are lead cores and cleaned a couple of times which many note alters pressing forces hence weight differences. Again jacket are annealed. Their surface area is far greater than the cups or anvils that don' go through the same process. Perhaps Aaron could comment on that or others who make their own. I know when involved with making barrels the quality assurance certificate was always re-checked because many a time it did not match the steel certification. Stuff happens. So it pays to check. David.