Vertical Dispersion - Weighing Primers

[Ned Ludd]

I like guys that don't test and believe in numbers. They are usually the ones that are easier to beat. Numbers don't always tell the truth. A good example is a chronograph ES verses actual target results.

Sometimes it is easy to color 5 bullets one color and 5 bullets another color, load them with the two different things and shoot them round robin in half decent conditions, sometimes the results are really easy to see and enough difference to see the difference. If still unsure, repeat the test again. Most times, what differences are clear enough to see, it repeats again. That way I save a lot of rounds on my barrel and can test a theory. Matt

Matt - we have briefly discussed the idea of sorting primers before and I certainly accept your description of the results on the target, even if I don't fully grasp why it should work the way it apparently does. Along those lines, if you were to fire 5 or 10 rounds (each) loaded with the extreme lowest and highest weight primers from a single Lot#, would it possible to detect some level of velocity change such as a difference in average velocity, or at least in ES/SD between the low/high weight primer sets? If not, what could be the explanation of why sorting primers by weight, and therefore, at least in theory, brisance, might work? I totally get the idea of total primer weight directly relating to the amount of priming compound. But I would [perhaps naively] also expect to see some measurable difference in average velocity, or at least ES/SD, accompanying the results observed on the target face.

 

[mikeeg02]

My 450s range 3.62-3.76 grains.

My 205m's range from 3.62-3.72 grains.

Funny I dont see anyone reporting weights of Federal GM Match primers...

Those above were gm205m's. I didnt know there was any other way to buy 205m's.

 

[mikeeg02]

Matt - we have briefly discussed the idea of sorting primers before and I certainly accept your description of the results on the target, even if I don't fully grasp why it should work the way it apparently does. Along those lines, if you were to fire 5 or 10 rounds (each) loaded with the extreme lowest and highest weight primers from a single Lot#, would it possible to detect some level of velocity change such as a difference in average velocity, or at least in ES/SD between the low/high weight primer sets? If not, what could be the explanation of why sorting primers by weight, and therefore, at least in theory, brisance, might work? I totally get the idea of total primer weight directly relating to the amount of priming compound. But I would [perhaps naively] also expect to see some measurable difference in average velocity, or at least ES/SD, accompanying the results observed on the target face.

I dont think you'll find it in the chronograph. In the chronograph I'd expect it to look like noise. The results will show up on paper. There's such little use for a chronograph in 1k paper. Again, it wont fix a 6" load. But it will help reduce the chance of fliers on a well tuned load.

 

[dmoran]

@Ned Ludd
With one of the worse Lot's of primers that I ever had (+7% weight variation), and firing them at random, from a rifle/load that was averaging around 3 to 3.5" groups at 1000yds from 5-shots in testing, I was getting flier aspects opening up some of the groups to +3.5 to 5.5". After weight sorting and calling out the extremes in that Lot, the flier aspect was eliminated and the rifle/load shot and acted like it had with the previous Lot of primers.

With that all said, the variation in primers was responsible for up to .2-MOA at 1000yds of dispersion increase. Fairly obvious to measure and see physically on the targets, but not much on the chronograph, with the maximum ES around 12-fps for all strings. Like @dkhunt14 and @mikeeg02 alluded above; easily lost in the noise of a chronographs accuracy levels.

 

[Rocketvapor]

After sorting enough you should end up with some "culls", both light and heavy.
Shoot the culls for group

 

[tom]

Funny I dont see anyone reporting weights of Federal GM Match primers...

I have every single CCI made on hand for testing, SR and LR, but always seem to find more accurate loads with Federal. I havent weighed any primers yet, but curious if the Federal GM Match primers are more consistent in weight.

I will weigh them myself eventually, but am curious about others sorting them

I'll check when I get home. Every barrel is different, I have 3 Kriegers all on my reamer, shooting 3 different primers. Which is part of the reasoning behind my first post to the OP.

Tom

 

[Rocketvapor]

Man, this has been an issue for years.
Just finished reading some older threads on this and other forums.
Conclusion? Not yet.
But here are some of my observations That don't carry any weight because I don't shoot as well as you guys.

Most of my practice is at 100 yards because that's what I have regular access to.
My 600 yd shoots are matches for score as I try to improve.
My previous position was sorting primers was ridiculous, but now subject to change.

What I find odd is that many precision shooters don't know how to weigh things.
Your scale does NOT need to be traceable. Single point calibration does not PROVE your scale is good.
As a retired Metrologist, most high level weighing use a scale/balance as a comparison device.
Comparing a know weight (mass) to an unknown with a technique to determine direction and magnitude of the difference.
Most "Labs" use reference standards directly compared to working standards for daily use.
Sensitivity of the balance is tested to validate the difference reading.
Does 2.000 grams show a repeatable and different result than 1.999 or 2.001 grams?

In reloading, many Calibrate their scale at some really LARGE value, like 50 grams and expect it to read correct at 2 grams.
Accuracy of small values on digital scales are also masked by the zero capture of the scale and rollover of least digit display. Scale electronics are often designed to try and eliminate short term drift of the zero. That hurts reading accuracy (percentage) at small values.
To measure small values, test with known small values.
To determine accurate weight, use know weights.
To sort heavies from lighties test with weights that are stable.

The U.S. Nickle is a good STABLE reference. Sort of close to 5 grams, not good enough to calibrate a scale with, but durable under protected use and handling. Mark and use the same nickle, it's pretty darn stable. Good enough to find light and heavy nickles.
Try it with your super duper scale. Can you SORT nickles?

Don't use scales excuses for NOT sorting primers.
Not enough spare time, fine.
Unproven gains, fine.
Scale ain't good enough, BULL.

 

[Ledd Slinger]

Those above were gm205m's. I didnt know there was any other way to buy 205m's.

Missed that. Thanks

 

[Ledd Slinger]

Most use the CCI in their 6MM because of harder cups, the primer piercing thing. I use Federal in my WSM. I don't see much difference between match and regular in weight differences. I also see no difference in accuracy between the two. So, if I weigh my primers, it's like getting paid to do it, the difference in price between the regular and match. Matt

I agree theres not much difference between standard 205s and 205 Match. They will shoot the same loads very similarly. But I have had a couple rifles that slightly prefer the Match over the standard and it's very repeatable on paper. On th flip side, I have had a couple rifles that prefered the standard 205 over the match.

Because theres usually not much difference, I only use standard 205s on my varmint rifles due to the sheer volume of rounds I load for them. Definitely saves a little coin

I just hate how much real estate the Federal primers take up on my storage shelf. Wish they would make them in smaller cases like everyone else.

 

[Ned Ludd]

I dont think you'll find it in the chronograph. In the chronograph I'd expect it to look like noise. The results will show up on paper. There's such little use for a chronograph in 1k paper. Again, it wont fix a 6" load. But it will help reduce the chance of fliers on a well tuned load.

How? There has to be some mechanism by which it works to improve groups. What is it? That's what I'd really like to understand.


As far as the "proper" balance necessary to effectively weigh and sort primers, it all depends on the total weight range within a given Lot#. In many cases, it might be as low as a few milligrams total spread. 0.02 gr is equivalent to ~1.3 mg. A balance with .02 gr readability likely has accuracy of +/- .04 gr or worse. Using such a balance to measure primers that might only have a total weight range of around 0.1 gr is not ideal. The total range of what you're trying to measure is only about twice the weight that represents the very best accuracy limit of the balance. It's all about understanding the limiting factor of measurement with a given instrument. It would be analogous to trying to weighing powder on a balance that could only read down to 10 gr, or trying to accurately weigh an item of between between one and ten pounds on a digital bathroom scale. Sure, the balance might give you a number, but it may not mean much in terms of accuracy or precision.

 

[mikeeg02]

I believe you're still thinking of it in the wrong mindset, which is why I keep stressing things the way I have been. When you can get a rifle tuned to shoot (at 1k) 3" or better for ten shots when the conditions allow it, you have a well tuned rifle, and shooting that small (especially for ten shots) is rarely an accident. When you have a load/rifle that does that, in order to repeat it, you need to do your best to be on what I call "flier management". This generally comes down to being as consistent, in every aspect (some things that many don't ever even think of). Some issues can be self induced, and some issues can be hard to track down. But consistency in everything is the key. People can shoot good single targets at any single time, and that can be for a number of reasons. When it comes down to aggregates and trying to follow up to that group, you need to have your equipment right so that it is capable every time, and eliminate every variance you can. A lot of people do not and will not understand that, until they have tried to shoot an aggregate.

Weighing primers isnt necessarily the best way to sort them (not that I've developed a better way), but its certainly better than not at all. And one of the few logical ways to do so. Because they are made of several components that we cannot individually check, I can see why some rational minds would say its a useless measurement. But again, its better than not at all. As shown in here, some lots have more variation than others. And every now and again you may find one outlier, that you sure as hell dont want in your record string. Consistent ignition is very important at 1k paper. I am not the first person to say this, and I wont be the last. Thats why weak firing pin springs can open up groups as well.

Im not going to argue with you about scale performance, repeatability, etc, because I see and understand what you're saying about that. That can be an issue with "lower" grade scales. And thats why I have the scale I have. For repeatability sake, when I calibrate the scale, and start sorting again I have some left over in the labeled box, and the leftovers always measure exactly what they did before. While I dont care for the "accuracy" of the measurement, I do care for it to be a repeatable value. The actual value has little merit to me, but the repeated value has all the merit to me.

 

[dkhunt14]

Matt - we have briefly discussed the idea of sorting primers before and I certainly accept your description of the results on the target, even if I don't fully grasp why it should work the way it apparently does. Along those lines, if you were to fire 5 or 10 rounds (each) loaded with the extreme lowest and highest weight primers from a single Lot#, would it possible to detect some level of velocity change such as a difference in average velocity, or at least in ES/SD between the low/high weight primer sets? If not, what could be the explanation of why sorting primers by weight, and therefore, at least in theory, brisance, might work? I totally get the idea of total primer weight directly relating to the amount of priming compound. But I would [perhaps naively] also expect to see some measurable difference in average velocity, or at least ES/SD, accompanying the results observed on the target face.

I havent chronographed anything except hunting rounds to get drops, in years. I have not found any useful information for 1000 yard BR. Most the info I get from a chrono just doesn't make sense of what the target tells you. I hope this makes sense to you. It could probably show a velocity difference but I believe like Mike, it would get lost in the noise.

It goes back to the same info of why the low ES almost never outshoots the slightly worse ES. The vertical on my extremely low ES never is less then another load of higher ES. I am talking an ES of maybe 2 or 3 verses an ES of 8 to 10. In fact most times that low one is almost always vertical. This is why i dont use a chrono because to me, it just clouds the picture. I never saw a target where they measured ES but the group is what they measure. I know that the difference between BR and F Class could change some things slightly. But in my mind I can't see why a consistent 4 inch vertical load wouldn't out score a 5 or 6 inch vertical load. Matt

 

[dkhunt14]

Man, this has been an issue for years.
Just finished reading some older threads on this and other forums.
Conclusion? Not yet.
But here are some of my observations That don't carry any weight because I don't shoot as well as you guys.

Most of my practice is at 100 yards because that's what I have regular access to.
My 600 yd shoots are matches for score as I try to improve.
My previous position was sorting primers was ridiculous, but now subject to change.

What I find odd is that many precision shooters don't know how to weigh things.
Your scale does NOT need to be traceable. Single point calibration does not PROVE your scale is good.
As a retired Metrologist, most high level weighing use a scale/balance as a comparison device.
Comparing a know weight (mass) to an unknown with a technique to determine direction and magnitude of the difference.
Most "Labs" use reference standards directly compared to working standards for daily use.
Sensitivity of the balance is tested to validate the difference reading.
Does 2.000 grams show a repeatable and different result than 1.999 or 2.001 grams?

In reloading, many Calibrate their scale at some really LARGE value, like 50 grams and expect it to read correct at 2 grams.
Accuracy of small values on digital scales are also masked by the zero capture of the scale and rollover of least digit display. Scale electronics are often designed to try and eliminate short term drift of the zero. That hurts reading accuracy (percentage) at small values.
To measure small values, test with known small values.
To determine accurate weight, use know weights.
To sort heavies from lighties test with weights that are stable.

The U.S. Nickle is a good STABLE reference. Sort of close to 5 grams, not good enough to calibrate a scale with, but durable under protected use and handling. Mark and use the same nickle, it's pretty darn stable. Good enough to find light and heavy nickles.
Try it with your super duper scale. Can you SORT nickles?

Don't use scales excuses for NOT sorting primers.
Not enough spare time, fine.
Unproven gains, fine.
Scale ain't good enough, BULL.

Testing at 100 yards, I believe will not show the results I need to see. I am sure the primer difference will not show much. 600 yards I believe will start to show it more. I know in my individual testing throughout the years showed me more things are easier to see at 1000 yards verses the 400 I tested at home with.

As far as the scales goes, this is why I use a Sartorius Entris 64. Do I need that extra digit to get accurate enough to shoot 1000 yards? The answer is no, but that extra digit makes my scale 10 times more accurate. It is all about repeatability. Matt

 

[dkhunt14]

I agree theres not much difference between standard 205s and 205 Match. They will shoot the same loads very similarly. But I have had a couple rifles that slightly prefer the Match over the standard and it's very repeatable on paper. On th flip side, I have had a couple rifles that prefered the standard 205 over the match.

Because theres usually not much difference, I only use standard 205s on my varmint rifles due to the sheer volume of rounds I load for them. Definitely saves a little coin

I just hate how much real estate the Federal primers take up on my storage shelf. Wish they would make them in smaller cases like everyone else.

Maybe the reason that match in one gun has shot better then regular in another is because that one lot was just closer in weight. I have weighed a bunch of lots of both and it just varies from one to another as to which weighs better. Some lots of primers just weigh great and some don't. Now I just use Regular, because they cost less. Matt

 

[dkhunt14]

How? There has to be some mechanism by which it works to improve groups. What is it? That's what I'd really like to understand.


As far as the "proper" balance necessary to effectively weigh and sort primers, it all depends on the total weight range within a given Lot#. In many cases, it might be as low as a few milligrams total spread. 0.02 gr is equivalent to ~1.3 mg. A balance with .02 gr readability likely has accuracy of +/- .04 gr or worse. Using such a balance to measure primers that might only have a total weight range of around 0.1 gr is not ideal. The total range of what you're trying to measure is only about twice the weight that represents the very best accuracy limit of the balance. It's all about understanding the limiting factor of measurement with a given instrument. It would be analogous to trying to weighing powder on a balance that could only read down to 10 gr, or trying to accurately weigh an item of between between one and ten pounds on a digital bathroom scale. Sure, the balance might give you a number, but it may not mean much in terms of accuracy or precision.

Your first sentence says everything to me. Everytime i use a chronograph, I ask the same question. How can a load of 2 ES shoot 13 to 15 inches of vertical at 1000 and a slightly different load of 12 to 15 ES shoot 4 inches of vertical? I have seen this many times with different guns or different cartridges that just makes me scratch my head. This is one of the main reasons, I don't use a Chrono to settle on loads. Matt

 

[rardoin]

View attachment 1162608 When I read threads like this I get thinking I am skipping a step but then I remember this. I’m not knocking your efforts but this load in my rifle does this all time. Admittedly it’s not at 1,000 but it’s pretty flat.

Incredible. I’d say you are in the node for certain.

 

[tvaught]

View attachment 1162608 When I read threads like this I get thinking I am skipping a step but then I remember this. I’m not knocking your efforts but this load in my rifle does this all time. Admittedly it’s not at 1,000 but it’s pretty flat.

Sir, that's an outstanding target.

I have seen targets very similar to these (several instances actually) with electronic target frames that got the sensor hub wires crossed.

It might be worth investigating the target and/or the load/tune before your next big match.

Don't mean to derail the topic at hand.

 

[JFrank]

I’m weighing primers from now on

 

[Ned Ludd]

Other than as a guess at a possible mechanism, I am not making any claims that the way in which weight-sorting primers improves precision in long range BR groups must be by affecting velocity. An effect on velocity would make sense, but that doesn't mean that must be the correct explanation. The only assertion I will make is that there must be some explanation for why it works. Whatever that explanation might be, there has to be one, even if we don't know what it is. I like knowing why things work in terms of accuracy/precision, for a lot of reasons. If sorting primers by weight improves groups, there has to be a reason why. If it's not velocity, it must be something else. If it's some property that has yet to be defined, or that is so subtle that the methods we typically use as analytical tools (such as velocity) are not capable of detecting it, so be it. It won't be the first time I've had to do something for which I simply had to accept that it worked, even if I couldn't explain why. Nonetheless, I feel certain there is such an explanation for why sorting primers by weight appears to improve precision, and I'd like to find out what it is if at all possible.

 

[Rocketvapor]

Assuming a shot string of adequate number of rounds, SD really doesn't come into play.
Keeping track of velocities and the shot number, run 10 shots, calculate SD, then exclude a ES outlier (IF it happened) and recalculate SD.
If there was NO ES outlier, repeat. Don't delete more than 9 shots in a ten shot string though.
It's the oddball that is to be caught, before it happens.
I'm sure everyone would like to eliminate all fliers, but cutting out ONE potentially caused by a rouge primer is a point for those that shoot for score.
Wind has nothing to do with fliers caused by a primer. Wind is wind, especially for the 20 minute prone shooter.
If I could prevent one of my few fliers I would have higher scores.