sorting cases by velocity?

[roklock]

First, just want to preface I am really a novice in 1000 BR and FClass. Also just trying to understand the "why".

In my searches, there is a lot of discussions on sorting brass by weight or volume but little to nothing of sorting by velocity, Why? Isn't velocity is determined by pressure which is the premise behind sorting cases by capacity or weight?

Am i way off base? What if I wanted to test, what would be a good way to do it and remove as many variables as possible? Shoot X number of brass, record each velocity and group into a +/- of X, reload and shoot groups from the two groups of velocity extremes?

Available list of current components list below:

Fully prepped twice fired Peterson 6BR brass, now 6BRA. (Annealed, sized, trimmed to same length)
scale that is +/-0.02gn
bullets are Hammers
450 primers (weighed)

 

[Dusty Stevens]

Give it a test and see what you come up with. An easy way to see if the test is even worth doing is shoot the same 5 brass 5 times and see if the velocity is the same each time on each piece

 

[newbieshooter]

First, just want to preface I am really a novice in 1000 BR and FClass. Also just trying to understand the "why".

In my searches, there is a lot of discussions on sorting brass by weight or volume but little to nothing of sorting by velocity, Why? Isn't velocity is determined by pressure which is the premise behind sorting cases by capacity or weight?

Am i way off base? What if I wanted to test, what would be a good way to do it and remove as many variables as possible? Shoot X number of brass, record each velocity and group into a +/- of X, reload and shoot groups from the two groups of velocity extremes?

Available list of current components list below:

Fully prepped twice fired Peterson 6BR brass, now 6BRA. (Annealed, sized, trimmed to same length)
scale that is +/-0.02gn
bullets are Hammers
450 primers (weighed)

I do this as a rough sort to weed out any outliers.

Bart also sorts using this method:
http://forum.accurateshooter.com/th...-by-h2o-capacity.3966683/page-2#post-37376226

 

[dellet]

Number the cases and shoot them in order so you can match velocity to case on the chronograph over multiple strings.

It’s also helpful to be able to mark your shots and at times eliminate the odd flyer, as in #3 always hits outside the group. Sometimes it shows in velocity, some times not.

You can also index a single case and sometimes shoot a pattern by rotating 90 degrees.

 

[roklock]

Give it a test and see what you come up with. An easy way to see if the test is even worth doing is shoot the same 5 brass 5 times and see if the velocity is the same each time on each piece

So, I wouldn't expect the same velocity every time, just consistent velocity in the "match set". So using your idea, I'm thinking I could shoot 20-30 pieces and then pick 5-10 that all have the same velocity or within a +/- 1 fps. Then I could shoot those 5-10 pieces of brass 3-5 more times to see if they would stay within that +/- 1fps of each other.

Thoughts on this approach?

 

[roklock]

It’s also helpful to be able to mark your shots and at times eliminate the odd flyer, as in #3 always hits outside the group. Sometimes it shows in velocity, some times not.

Interesting observation, thanks.

 

[roklock]

I do this as a rough sort to weed out any outliers.

Bart also sorts using this method:
http://forum.accurateshooter.com/th...-by-h2o-capacity.3966683/page-2#post-37376226

Thanks for the link to that thread...you mention velocity is your rough sort are you also weighing the brass or measuring volume?

 

[Dusty Stevens]

So, I wouldn't expect the same velocity every time, just consistent velocity in the "match set". So using your idea, I'm thinking I could shoot 20-30 pieces and then pick 5-10 that all have the same velocity or within a +/- 1 fps. Then I could shoot those 5-10 pieces of brass 3-5 more times to see if they would stay within that +/- 1fps of each other.

Thoughts on this approach?

Give it a try and see. Youll find some kind of pattern somehow i think

 

[Ned Ludd]

The notion of using velocity as a readout to sort brass might be viewed in at least a couple different ways. One way would be a set of cases that produce uniform velocity on any given firing through repeated brass preps. In that scenario, it's not difficult to envision there might be subtle changes in velocity from loading to loading, but the velocities among the pieces of brass in the set would remain very uniform on any given firing.

Another way to think about it would be to assume that certain pieces of brass associated with unacceptable velocity outliers would continue to do so through repeated loadings. Those pieces could simply be removed from a set, thereby also leading to more uniform velocity among the remaining pieces. Regardless of the scenario, either creating a uniform set of brass by combining the pieces that behave similarly, or culling those that do not, only rigorous testing will allow you to determine how well such a brass sorting procedure will work in your hands.

 

[LC Tikka]

Everything put into a case has some differences, once you are satisfied your practices during loading are the best you can control, then the case itself should be considered as another variable.
In the ideal situation pressure equals velocity, if variations in velocity are the result once all other steps in loading are equal, the case would be the cause. Case volume if all equal would then produce equal pressure and velocity. Sort cases by volume and move ahead knowing you have done your very best.
LC

 

[dcali]

You’re well into diminishing returns when you start looking at this. I would start with something simple like sorting cases by weight or volume. Isolating variables makes science a whole lot easier.

 

[JFM33]

I tried sorting by weight and noticed there was velocity highs and lowes.
I enjoy shooting and it's pretty simple to shoot and record velocity then I just sort the brass that shot higher for the early relays and the lower for the afternoon.I do this in hopes of staying in the sweet spot. It's like pointing bullets I do it if I have the time and if there's and let up or switch that I miss neither will matter.

 

[R.Morehouse]

Bob ( The Viper) Pastor did this for his 6.5-06imp. He would sort 1K cases into small groups with an ES of zero and keep them together. He would preload ALL of them and soft seat them on the line. His load wasn't real sensitive to changes due to throat erosion so by the time he would get back from shooting F in the Great White North the ammo was for the most part gone & so was the new Broughton barrel he started out with.....Oh Yeah.....And he did a WHOLE LOT of winning.

Regards
Rick

 

[JFrank]

You’re well into diminishing returns when you start looking at this. I would start with something simple like sorting cases by weight or volume. Isolating variables makes science a whole lot easier.

Sorting by volocity and effect on accuracy should be the way forward.
I’m also saying who cares if the case weighs more than the rest or how much water can it hold we want to cull out the outliers as pointed out earlier in this thread.
J

 

[CharlieNC]

The effect of velocity depends upon where you are with respect to the harmonic node of the barrel. If you carry out a ladder type of test you will find the charge weight which places you in the node, then optimize seating depth (or vice versa if you prefer). If you are not within this node, then the effect of velocity depends greatly upon the distance you are shooting and at, and short ranges may not even show up due to other inconsistencies. But developing a load within a good node is paramount and requires proper choice of bullet, powder, etc as well as just carrying out charge weight and seating depth trials.

For example I have a new barrel on my 6.5x47 and carried out a load development using same components as before, but settled on 0.4gr less powder than before based on evaluation at 200yd to id the node. This week at the long range I expected adjustments due to lower velocity, but the zero and dope was the same out to 1000yd as the old load which I shot as well. Power of the node vs velocity deviations!

 

[mikecr]

Why?

I salute your attitude. It is so rare that anybody wonders WHY..

I believe your MV sorting notion holds merit equal to any other.
IMO, sorting cases by weight variance is just a shortcut to nothing real.
In contrast, matching actual H20 capacities could contribute directly to uniform velocities.
Without going into best practices to achieve and manage matched capacities, let's talk about WHY this would work to lower ES -as born from cases alone.

It doesn't take a lot of searching to find folks describing that their new cases produce lower velocities than fully fire formed cases. This is because new cases change more on 1st firing, and the energy to do this is taken from pressure peaks(lowering MV). Fully formed cases change less on firing, taking less energy from pressure peaks(raising MV).
With your searching you would also find that many shooters are very happy with results from new cases. But unfortunately, the results are often fleeting to that condition. This is because the energy taken from pressure peaks served to provide a forgiving plateau. Just once.

Forgiveness and average velocity aside, case expansion energy does affect velocities.
I'm confident that case weight and even case volume are petty to case expansion energy. Otherwise, new cases, that certainly do not match in volume yet, would not likely shoot so well.
So what affects case expansion energy?
That would be chamber clearance, case thickness and hardness, and case personality.
Personality, relating to lowest static energy states for individual cases. This changes with energies added through up/down sizing, as cases want to go where they've been. Sounds like hardness, I know, but think of it as memory instead. Different from hardness.

Once you've fully fire formed cases to stable, the point where successive firings produce no further changes, you're at a point where H20 capacities would be measured & matched. If the cases expanded and sprung back through several reload cycles to end up matching in H20 capacity, then it is very likely that they match in expansion energy as well. They hit chamber walls and still spring back to same volume. They suffered whatever your sizing, and still spring back to same volume. Right?

Now if you're looking for another shortcut to work around H20 capacity matching, you might assume it's easiest to toss cases by velocities. But to KNOW this is appropriate takes more shooting than measuring.
I think it could work, and that it's merely a choice for you to make. Shoot more, or measure more.

 

[JFrank]

^^^Dang
That was really good...

 

[dogdude]

I do this as a rough sort to weed out any outliers.

Bart also sorts using this method:
http://forum.accurateshooter.com/th...-by-h2o-capacity.3966683/page-2#post-37376226

I'm with Bart, its easy..I take the ones that are closest in #'s, then put them in a Red brass baggie so it doesn't matter if the magic marker rubs off..next #'s a green baggie and so on.
Just bought a case marker (haven't tried yet) too alleviate separating before tumbling or sonic cleaning.

 

[roklock]

Just bought a case marker (haven't tried yet) too alleviate separating before tumbling or sonic cleaning.

What case marker did you get?

 

[whatwind?]

I salute your attitude. It is so rare that anybody wonders WHY..

I believe your MV sorting notion holds merit equal to any other.
IMO, sorting cases by weight variance is just a shortcut to nothing real.
In contrast, matching actual H20 capacities could contribute directly to uniform velocities.
Without going into best practices to achieve and manage matched capacities, let's talk about WHY this would work to lower ES -as born from cases alone.

It doesn't take a lot of searching to find folks describing that their new cases produce lower velocities than fully fire formed cases. This is because new cases change more on 1st firing, and the energy to do this is taken from pressure peaks(lowering MV). Fully formed cases change less on firing, taking less energy from pressure peaks(raising MV).
With your searching you would also find that many shooters are very happy with results from new cases. But unfortunately, the results are often fleeting to that condition. This is because the energy taken from pressure peaks served to provide a forgiving plateau. Just once.

Forgiveness and average velocity aside, case expansion energy does affect velocities.
I'm confident that case weight and even case volume are petty to case expansion energy. Otherwise, new cases, that certainly do not match in volume yet, would not likely shoot so well.
So what affects case expansion energy?
That would be chamber clearance and case thickness and hardness.

Once you've fully fire formed cases to stable, the point where successive firings produce no further changes, you're at a point where H20 capacities would be measured & matched. If the cases expanded and sprung back through several reload cycles to end up matching in H20 capacity, then it is very likely that they match in expansion energy as well. They hit chamber walls and still spring back to same volume. They suffered whatever your sizing, and still spring back to same volume. Right?

Now if you're looking for another shortcut to work around H20 capacity matching, you might assume it's easiest to toss cases by velocities. But to KNOW this is appropriate takes more shooting than measuring.
I think it could work, and merely a choice for you to make. Shoot more, or measure more.

is alcohol better to use for capacity because it more consistent than water?