I started improving my reloads by first separating my brass by headstamp, then by weight. Now I am starting to separate my brass by volume/weight. Yet, the brass weight can vary even though the volume is the same. Have any of you noticed improved accuracy with brass with the same volume when you had originally separated them by weight?
Tell me I'm doing the right thing
- Thread starter BJung
- Start date
Jager
Gold $$ Contributor
The problem with sorting brass by volume is that it is a painfully slow, tedious process. But volume is ultimately what matters... so if you somehow find a way to do that - accurately measure volume - that's what you want to focus on.
Sorting by weight is simply a proxy for volume... the assumption being that there is a correlation between the two. And it's a quick and easy thing to do. Alas, many of us don't believe that correlation is nearly as strong or as consistent as we would wish.
Volume is what matters. But I can't say I've ever met a handloader who measures volume in anything other than small sample sets.
Sorting by weight is simply a proxy for volume... the assumption being that there is a correlation between the two. And it's a quick and easy thing to do. Alas, many of us don't believe that correlation is nearly as strong or as consistent as we would wish.
Volume is what matters. But I can't say I've ever met a handloader who measures volume in anything other than small sample sets.
You didn't mention your shooting discipline. As I'm not a benchrest or long range "F" class shooter, just a precision varmint / predator shooting with modest 1/2" moa goals so take that into account regarding my opinion of this subject.
I believe there is merit in dedicating a specific group of cases from the same lot (I use 50 since it's convenient because that is the way they are sold) to a specific rifle and rotating their use so all the cases received the same amount of wear, sizing, etc. I believe this aids in consistency for sizing and while I can't prove it, it would seem that this would also contribute to more accurate reloads.
Beyond that, for my purposes, I see no value in going any further and incurring the tedious and laborious process of separating cases by weight and volume. I certainly would not toss out new cases that have different weights or volumes. Keeping track of all that would turn a hobby into a painful endeavor.
I believe there is merit in dedicating a specific group of cases from the same lot (I use 50 since it's convenient because that is the way they are sold) to a specific rifle and rotating their use so all the cases received the same amount of wear, sizing, etc. I believe this aids in consistency for sizing and while I can't prove it, it would seem that this would also contribute to more accurate reloads.
Beyond that, for my purposes, I see no value in going any further and incurring the tedious and laborious process of separating cases by weight and volume. I certainly would not toss out new cases that have different weights or volumes. Keeping track of all that would turn a hobby into a painful endeavor.
Ned Ludd
Silver $$ Contributor
As others have mentioned, sorting brass by water volume is slow and painful. However, it is the best way to obtain groups of cases with more uniform internal volume. Sorting cases by weight is a "surrogate process" for sorting them by volume. It works, meaning that as long as you are sorting cases by weight that represent the same brand and [preferably] Lot#, you can generally obtain groups of cases with less internal volume variance than if you did not sort them at all.
I typically sort cases into three weight groups: light, medium, and heavy. To determine the cutoffs for each group, I first weigh 50-75 cases and record the values, after which each case is placed in order into a loading tray so that I know the weight of each case and don't have to weight sort them a second time. I then determine the overall range of case weights, then make a crude estimate (eyeball) of where the cutoffs should be for each group.
It is worth mention that by the time I have sufficient numbers of cases to sort by weight, I have already determined the actual water volume for 10 cases at least a couple or three times as part of my initial load development process. As a part of that procedure, I weigh each of the 10 empty and unprimed cases that will be used for water volume determination before loading. That way, I can make a scatter plot in a graphing program of case volume versus case weight, then use the program to do simple linear regression curve fit and determine the correlation coefficient, a measure of how good the "fit" of the data points are to a straight line. In other words, I already have a very good idea of how well case volume correlates to case weight for a particular Lot# of brass before I ever start sorting the brass into weight groups. This is an important initial step in the process so that you are confident the weight sorting approach actually IS a good surrogate for sorting cases by volume.
The next thing to consider before embarking on the "sorting cases by weight" journey is what are your expectations at the end of the sorting process? You mentioned "improved accuracy" in your initial post. I have to tell you that you may not observe any effect on "accuracy" at all by sorting brass, especially if your readout of accuracy is obtained by shooting groups at short distance, let's say 100-200 yd. The whole point of sorting cases by weight (or volume) is to maintain the most uniform velocity possible, just like weighing powder to +/- one kernel. In other words, what we are after when we sort cases by weight (or volume) is the best precision with regard to velocity. Sorting cases by weight (or volume) may not have a noticeable effect on accuracy at all, unless you are shooting at a sufficient distance that velocity variance due to case volume variance has an effect on precision, largely vertical. Alternatively, you might notice an effect at shorter distances, but that will typically require a rifle/setup/shooter capable of extreme accuracy/precision.
As I mentioned above, I sort cases by weight into light/medium/heavy groups. I know with certainty that in my hands and with the specific brass I'm using, the weight sorting process generates groups of cases with more uniform internal volume. What I cannot state with certainty is whether that actually makes a difference in my match score (F-TR). I believe it does over the long haul, or I wouldn't do it. The good news is that sorting cases by weight is relatively fast and simple, so you're not expending a huge amount of effort on a process for which it is relatively difficult to substantiate positive results. Unfortunately, some of the things we do in the reloading process can be very difficult to substantiate or validate, except over the long run, and even then they may be difficult to quantify. Thus, every reloader has to consider their objectives, and the steps they will use to reach those objectives, and determine whether any particular step is actually worth their time/effort. Some things require a bit of faith, without necessarily ever receiving bona fide "proof" of their usefulness.
I typically sort cases into three weight groups: light, medium, and heavy. To determine the cutoffs for each group, I first weigh 50-75 cases and record the values, after which each case is placed in order into a loading tray so that I know the weight of each case and don't have to weight sort them a second time. I then determine the overall range of case weights, then make a crude estimate (eyeball) of where the cutoffs should be for each group.
It is worth mention that by the time I have sufficient numbers of cases to sort by weight, I have already determined the actual water volume for 10 cases at least a couple or three times as part of my initial load development process. As a part of that procedure, I weigh each of the 10 empty and unprimed cases that will be used for water volume determination before loading. That way, I can make a scatter plot in a graphing program of case volume versus case weight, then use the program to do simple linear regression curve fit and determine the correlation coefficient, a measure of how good the "fit" of the data points are to a straight line. In other words, I already have a very good idea of how well case volume correlates to case weight for a particular Lot# of brass before I ever start sorting the brass into weight groups. This is an important initial step in the process so that you are confident the weight sorting approach actually IS a good surrogate for sorting cases by volume.
The next thing to consider before embarking on the "sorting cases by weight" journey is what are your expectations at the end of the sorting process? You mentioned "improved accuracy" in your initial post. I have to tell you that you may not observe any effect on "accuracy" at all by sorting brass, especially if your readout of accuracy is obtained by shooting groups at short distance, let's say 100-200 yd. The whole point of sorting cases by weight (or volume) is to maintain the most uniform velocity possible, just like weighing powder to +/- one kernel. In other words, what we are after when we sort cases by weight (or volume) is the best precision with regard to velocity. Sorting cases by weight (or volume) may not have a noticeable effect on accuracy at all, unless you are shooting at a sufficient distance that velocity variance due to case volume variance has an effect on precision, largely vertical. Alternatively, you might notice an effect at shorter distances, but that will typically require a rifle/setup/shooter capable of extreme accuracy/precision.
As I mentioned above, I sort cases by weight into light/medium/heavy groups. I know with certainty that in my hands and with the specific brass I'm using, the weight sorting process generates groups of cases with more uniform internal volume. What I cannot state with certainty is whether that actually makes a difference in my match score (F-TR). I believe it does over the long haul, or I wouldn't do it. The good news is that sorting cases by weight is relatively fast and simple, so you're not expending a huge amount of effort on a process for which it is relatively difficult to substantiate positive results. Unfortunately, some of the things we do in the reloading process can be very difficult to substantiate or validate, except over the long run, and even then they may be difficult to quantify. Thus, every reloader has to consider their objectives, and the steps they will use to reach those objectives, and determine whether any particular step is actually worth their time/effort. Some things require a bit of faith, without necessarily ever receiving bona fide "proof" of their usefulness.
I would make the argument that any sorting should be done after the brass has been sized in your die so that all exterior dimensions (die touches neck, shoulder, and body) have been controlled by you, and any prep that changes the weight of the brass (trimming, turning, primer pocket uniforming, ect...) has been done.
Then either sorting method weight or volume works to produce more consistent reloads. But if you sort then remove material from the brass it will change the results of the sorting. Control and make consistent as many dimensions as possible and then sort. That is my advice.
Then either sorting method weight or volume works to produce more consistent reloads. But if you sort then remove material from the brass it will change the results of the sorting. Control and make consistent as many dimensions as possible and then sort. That is my advice.
As I posted not long ago, when I sorted a box of Lapua brass, I did find a significant difference. But, I wouldn't say much difference, if any, in "accuracy" . . . but in "precision". That is, the two groups of brass I used produced more consistent results with low SD's and low ES's. So, what I get from sorting brass (by weight) is more consistency by identifying the outliers that so often throw off an ES and set them aside.
Here's what that weight sorted box of Lapua .308 brass looked like (and yes, they were sorted AFTER having been fire formed, trimmed to length, primer pocket uniformed and neck turned but not sized yet, so the dimensions are pretty uniform):
The one group tested was column 5th & 6th from the left and the other group was the 3rd and 4th column from the right.
While I find that sorting by weight/volume works to get better consistency, I don't think you'll see much difference until one is shooting long or extreme distances. But I do like identifying the outliers at both ends of the range of measured weights and keeping them for a separate use.
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I need to ask a sincere question and this is not to start a pissing contest:
If powder charges are thrown without weighing to the kernel (as in most tabletop shooting) why be concerned about fractional differences in brass capacity?
Jeeeez I hope this doesn't start another pissing contest...
If powder charges are thrown without weighing to the kernel (as in most tabletop shooting) why be concerned about fractional differences in brass capacity?
Jeeeez I hope this doesn't start another pissing contest...
Hmmm. That's a fair question. I'd suppose that if one isn't concerned with the difference a kernel might make, then there doesn't seem to be any need to be concerned over variances in brass capacity . . . especially if one is using quality brass like Lapua. Certainly, there's going to be a big difference if one has a mixed batch of brass that might have Winchester brass along with Federal brass (for example) where the difference in their volume would show up as very noticeable on paper.
For me, all the little things add up. So I simply try to control all that I can control (or can afford to control).
I had my wife's meat injector ready to setup with my electronic scale to measure case volume when, by chance, I read a discussion on Long-range hunting that they use ball powder to fill their trimmed cases. I tried this on recently fired cases that were trimmed to the same length. Using the ball powder is much quicker and less messy. But then, I wanted to do the same with other brass I had. Unfortunately, they were resized and deprimed. So, I went to the hardware store yesterday and purchased this appliance part for 60 cents, cut it to the depth of my primer pocket with my pocket knife on my wife's cheese cutting board, and there you go. I attached photos for you to see the part. BTW, the plug leaked because of a groove on the finned shaft so I made a paper patch for the flash hole with a hole punch. In theory, I hope that using this ball powder works.
Attachments
True but then, what about concentricity! I have mandrels and some brands of cases are more concentric walls than others. If the thick part of the neck corresponds to a thicker wall on the same time, wouldn't it be better to insert your brass into your rifle chamber the same way? Whether you turn the case necks or not, the bullet ogive will contact the rifling at close to the same place, yes? Then, it's a good idea to sort by concentricity too, or atleast into A/B/and C groups.You didn't mention your shooting discipline. As I'm not a benchrest or long range "F" class shooter, just a precision varmint / predator shooting with modest 1/2" moa goals so take that into account regarding my opinion of this subject.
I believe there is merit in dedicating a specific group of cases from the same lot (I use 50 since it's convenient because that is the way they are sold) to a specific rifle and rotating their use so all the cases received the same amount of wear, sizing, etc. I believe this aids in consistency for sizing and while I can't prove it, it would seem that this would also contribute to more accurate reloads.
Beyond that, for my purposes, I see no value in going any further and incurring the tedious and laborious process of separating cases by weight and volume. I certainly would not toss out new cases that have different weights or volumes. Keeping track of all that would turn a hobby into a painful endeavor.
I fill my case with powder and pour the powder into the pan on my 505 RCBS balance.
Hoot
Silver $$ Contributor
I like the concept for ease of use but my experience has been that even the best ball powders settle a little differently depending upon how much you stimulate the case. It would seem that you would need a repeatable stimulus source for each of them to settle to the same extent, or am I overthinking this?
A timed vibe table would probably do the trick.
Hoot
I plan to shoot 300 yards and more. I have brass that I've resized but never fireformed. I plan to carefully trim them to the same length and find the most consistent volume among them. Again, I hope volume sorting works. My concern then is whether the energy used to expand these cases will affect accuracy compared to my current batch that are fireformed and neck sized.
I always throw a charge under my desired load and trickle up to my desired powder
weight.
Has anyone compared mv between loads that have been trickled up to a certain weight compared to volume alone?Hmmm. That's a fair question. I'd suppose that if one isn't concerned with the difference a kernel might make, then there doesn't seem to be any need to be concerned over variances in brass capacity . . . especially if one is using quality brass like Lapua. Certainly, there's going to be a big difference if one has a mixed batch of brass that might have Winchester brass along with Federal brass (for example) where the difference in their volume would show up as very noticeable on paper.
For me, all the little things add up. So I simply try to control all that I can control (or can afford to control).
I'm to understand you're talking about a fixed powder weight and the difference any difference in MV corresponding to the difference in case volume? If so, the answer is yes as that is one of the differences I found in my little experiment in my post #8 here. The group with the heavier cases had produced an average MV that was higher that the group of lighter cases (the difference being ~1.5 grs of H2O). I typically save such data, but I can't seem to find it for this test, or I'd share the actual numbers. Since I only did this test once with my .308 cases, it really not much more than anecdotal unless I can reproduce the experiment and get the same results.
Really? During a benchrest match? Cuz' my question was asked in regard to that realm. Just asking.
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I sort by H20 capacity only after 3rd fire forming, before any sizing.
That's what I load develop with.
After development, When I get a flyer, I toss the case.
It's not about weight at all, and not even directly about static volume.
It's about brass energy to reach chamber wall (dynamic volume).
If you measure & match capacities of chamber formed brass, FL size them, and re-measure capacities, you're likely to find a few leaving the pack. That sizing is adding energy for the brass to accept this or that much of. As the brass acts differently to sizing, it will act to expansion on firing.
Then if you FL size enough to need trimming, capacities are changing again. And if you change your annealing from case to case or as developed, you're affecting brass energy.
The more you do to matched cases, the faster they no longer match.
In reality, it takes more than effort to manage matched energies. You can't viably hold it with just effort.
Instead, it takes a specific plan to do so.
Part of that plan would include tossing the bastards.. Don't waste another shot from one.
That's what I load develop with.
After development, When I get a flyer, I toss the case.
It's not about weight at all, and not even directly about static volume.
It's about brass energy to reach chamber wall (dynamic volume).
If you measure & match capacities of chamber formed brass, FL size them, and re-measure capacities, you're likely to find a few leaving the pack. That sizing is adding energy for the brass to accept this or that much of. As the brass acts differently to sizing, it will act to expansion on firing.
Then if you FL size enough to need trimming, capacities are changing again. And if you change your annealing from case to case or as developed, you're affecting brass energy.
The more you do to matched cases, the faster they no longer match.
In reality, it takes more than effort to manage matched energies. You can't viably hold it with just effort.
Instead, it takes a specific plan to do so.
Part of that plan would include tossing the bastards.. Don't waste another shot from one.
I meant to say, has anyone compared test loads with the powder charge that was weighed with a trickler vs. test loads where the powder thrower was adjusted to throw a certain volume/weight and the powder just thrown afterwards. Did I read correctly that benchrest shooters do this?
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