Vertical Dispersion - Weighing Primers

[David Christian]

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.

You are absolutely correct. If @granite1, really shot that string at 600 yards, either sensor wires were crossed or they were running 2 hubs that were on the same channel. Happens all the time and produces a straight line in the vertical or horizontal. No one can shoot a string of 20 as a flat line. Or that target was really at 100 yards. Just saying...

You can send that raw file to Adam at Shotmarker and he can open it and show that it was not flat.

 

[dkhunt14]

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.

Maybe it has something to do with what Donovan said earlier and has to do with the ignitial push from the primer. Primers have alot of energy when they fire. Look how they can push a bullet with no powder down a barrel. Maybe it's from the initial push and doesn't show up much as A velocity thing. Matt

 

[Rocketvapor]

Take a powder, your favorite, charge for a specific velocity.
Take another powder and charge for the same velocity.
Get the same group sizes?
Try it again changing from a standard primer to a magnum primer (obviously under a max load) with the two powders, load for the same velocity.

Velocity doesn't mean squat.
Or we wouldn't have so many powders and primers being someone's favorite.
A different pressure vs time curve can give the same velocity but different down range performance.
Sure would make load development easier if muzzle velocity was the key factor.

 

[JFrank]

Personally, I don’t have to dissect it rather just make it part of my routine because if it helps manage fliers I’m gonna do it.

 

[Joe Salt]

Ok in my experience with primers all you have to remember at 1000 yards is you don't want one at 5.34 with one at 5.78 you won't like it. So if you want to try that just for Sh$$$ and giggles that is the way I would test.

Joe Salt

 

[mikeeg02]

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.

I agree with wanting to know why. And like Matt suggested above, we have some theories, but they are just that, theories. Most of us that experience these things spend a lot of time trying to figure out the why. Myself (and I know Matt and Donovan are the same way) try not to speak of things we dont fully understand. Or if we do, its as best as we understand it(not saying it never happens, but we try). Thats just the kind of people we are. We can tell you what we know it doesnt look like it affects, but to say we 100% are certain we know the why would be incorrect, therefore we are still working on that part, and dont want to make false misleading claims.

When you get a gun/load capable of shooting 4" or vertical or less at 1k, test it. See how many times you can repeat it. See what you have to do to maintain it. The point of all of this should not be to tell you whats right and wrong, its to give you ideas on things to test to the best of your abilities. A lot of BR guys have tested this, and given our experiences, its up to you to test and rationalize whether it works for you or not. Maybe you have hummer barrel and a load with a wide enough node you wont notice a difference. But if you do, I can just about guarantee you the next barrel will not act the same.

And one last time, I wish you would look at it as reducing the chance of flier. Not improving groups. While they sound the same, they are different. It doesnt fix a load, it helps to repeat/maintain it. You have to be able to read the target and the relay.

 

[Bindi2]

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.

If you have a tuner on your barrel it is not correctly tuned. The barrel is throwing side ways.

 

[Ned Ludd]

I agree with wanting to know why. And like Matt suggested above, we have some theories, but they are just that, theories. Most of us that experience these things spend a lot of time trying to figure out the why. Myself (and I know Matt and Donovan are the same way) try not to speak of things we dont fully understand. Or if we do, its as best as we understand it(not saying it never happens, but we try). Thats just the kind of people we are. We can tell you what we know it doesnt look like it affects, but to say we 100% are certain we know the why would be incorrect, therefore we are still working on that part, and dont want to make false misleading claims.

When you get a gun/load capable of shooting 4" or vertical or less at 1k, test it. See how many times you can repeat it. See what you have to do to maintain it. The point of all of this should not be to tell you whats right and wrong, its to give you ideas on things to test to the best of your abilities. A lot of BR guys have tested this, and given our experiences, its up to you to test and rationalize whether it works for you or not. Maybe you have hummer barrel and a load with a wide enough node you wont notice a difference. But if you do, I can just about guarantee you the next barrel will not act the same.

And one last time, I wish you would look at it as reducing the chance of flier. Not improving groups. While they sound the same, they are different. It doesnt fix a load, it helps to repeat/maintain it. You have to be able to read the target and the relay.

I most certainly appreciate your and Matt's responses. I also grasp the difference between eliminating a flier as opposed to improving overall group spread. Although there can be sometimes be a bit of overlap between the two in terms of the final readout, I agree that they are not the same thing. FWIW - I'm not a BR shooter. As an F-TR shooter, I'm not even particularly interested in weight-sorting my primers, because I don't view that as being the limiting source of error in the kind of shooting I do, and I doubt it would provide me with the same benefit for the investment of time. Nonetheless, as a scientist I find the concept intriguing and would simply like to better understand the mechanism by which it works. That's all, just a personal curiosity.

 

[granite1]

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.

I posted here simply to say that this subject got me thinking about the value of weighing not just to correct vertical but with my rifle and load, would it help me with horizontal spread. I posted the target to show what had occurred on one good day. There was nothing wrong with the target that day. I don’t use a tuner. And I think I am going to try weight sorting. What the heck, can’t hurt.

 

[MattPeetz]

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.

This is a classic crossed wires on the solo. Even if not, that is a horrible load. Would be horrible in the wind

 

[mikeeg02]

There was nothing wrong with the target that day.

Some of us have just seen that issue, and sometimes youll want to have a fresh paper backer to verify. When I first got my shot marker it was pretty windy. And I had the upper wires come around and inside of the lower sensors. (So they were properly connected, but the physical wire from the upper sensor had come between the lower sensor and the backer) My buddy thought he fixed the vertical on his 308. Everything looked like .200" of vertical at 500m, though not quite as much left and right as yours. We went down to look at the paper and that wasnt the case. Not saying thats your situation, but from past experiences, I would want a fresh backer every now and again so you can verify thats in fact whats going on. Since then I have screwed conduit clamps to the back to keep the wires from coming around the front at all. Remedied my issue.

Edit: Just to be clear, I am not doubting your target. I understand the struggles it takes to get a rifle to print a nice target, and have no reason to doubt you. I'm just offering my experience with that target so you hopefully dont run into the same issue I did.

 

[dmoran]

........ As an F-TR shooter, I'm not even particularly interested in weight-sorting my primers, because I don't view that as being the limiting source of error in the kind of shooting I do, and I doubt it would provide me with the same benefit for the investment of time.....

If scoring another 10 or two, or another X or two, isn't important to you, then definitely should invest your time else where.
But that is the kind of improvements F-TR / F-Class shooters could occasionally expect, from qualifying a poor Lot of primers.

You can argue the fact all you want and/or the reasoning's to why, but weight sorting/qualifying primers has repeatedly been proven by so many LR Benchrest shooters over so many years now, that it is an unarguable fact.

Sort to speak, if it can occasionally gain a 1000-BR shooter .2-MOA to a group, it can do the same for any discipline, and no matter what the accuracy level is, or how shrouded some test results may obscure the fact.

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[savageshooter86]

So I found my BR2 lot so far has had two at 5.10gr!!! The majority 5.20 to 5.26. And a decent number 5.28/5.32. And also had one 5.34. So 5.10 and 5.34 on a string might not be so good. That’s why I’m gonna test but I’ve already sorted mine

 

[tom]

Just for fun I did an experiment in the loading room, while sorting some 205s.

Here's a light full, and a heavy full, being dissolved of their compound with water. Hint, it speeds up the process to shake it.


Below is the dissolved primers drying.



The next couple below are their empty weights.





Sample size of 2, lol but it does appear about 66% of the weight you're sorting is compound. The heavy one is normally not a cull in my lot, but towards the heavy end. The light one was WAY OUT, and the photo below might explain where it came from.



This experiment is not indented to be scientific proof of anything, as I go about things by putting holes in paper for proof of anything I do or don't do.


Tom

 

[rsmithsr50]

tom,
where is the SEALANT weight in this "test " ?
cup
anvil
primer compound
sealant

 

[tom]

tom,
where is the SEALANT weight in this "test " ?
cup
anvil
primer compound
sealant

Visual inspection would say it's still attached. The only thing gone, best I could tell is the yellow compound itself.

Tom

 

[tom]

Cool test.....
Not often you will do a test that doesn't include putting holes in a target ... lol
A fairly significant variance in compound. Very interesting.
Thanks

Was on the phone with torgerson when I found that light one, and couldn't believe how light it was. It wasn't much out of my way to do it while continuing on my sorting. It's the first one outside of a tenth range in my lot...about the 1500th one weighed lol.

Tom

 

[Ledd Slinger]

I wish I had the time to do what @tom does...Lol

Hey Tom, can I bring these over and have you sort them all for me? That would be great...Thanks

 

[sqrlgtr]

OK My 2 cents.Thread was started back in 2011 and its 10 pages long and was just wondering if anyone has put up one of them voting polls to see what the results would be?I know weighing primers makes a difference for me but thought it would be interesting to see results of said poll.I would do it myself but afraid I would do it wrong lol..Maybe someone who is not so computer illiterate as me could do it....

 

[Rocketvapor]

Targets pics are enough.
Start a thread about seating bullets backwards and you'll get target pics