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VT52
01-12-2013, 04:58 PM
Maybe interesting for some folks, old news for others... Someone at the club asked why people weigh brass and I looked up some figures to try to explain a little about the sense, or non-sense, for doing this (not just for BR, for plane-jane rec shooters as well).



Brass = 8400 kg/m3

Air = 1.29 kg/m3

Vihta N133 = 870 kg/m3


1 grain of brass displaces 1.29/8400 = 0.000153 grains of air

1 grain of brass displaces 870/8400 = 0.965 grains of powder

1 kernel of N133 weighs around 0.025grs

So 1 grain in case weight gives the same result as 0.1gr of powder (in terms of volume, not weight), ie 3-4 kernels of N133.


Depending on what you shoot (BR, plinking, high-power), that 0.1gr powder volume difference may mean nothing, or it may mean something. I can not, however (imho), see how sorting at the 0.1gr level of brass weight would mean anything, besides on paper, to real world results, as this would mean 0.01gr less volume for the powder.

Joe Salt
01-12-2013, 05:11 PM
VT52 when your shooting 1000 yards everything makes a difference, try weighing primers also, there can be a big difference. At 100- 200 not so much! Remember for every action there is a reaction in loading. One thing at a time so you know what done what.

Joe Salt

VT52
01-12-2013, 07:06 PM
I don't shoot BR at 1000, only F-Class. When I'm guessing to add or drop 2 minutes of wind I don't think 0.01grs case volume will make a difference to me ;). It all depends what game you are playing.

RegionRat
01-13-2013, 03:29 AM
Another observation to add to the mix.
Over the years, I used to start with 100 Lapua .30-06 cases to make a seasons worth of elk cartridges. As time went on, I noticed I had to start with 200 to make sure I could sort out about 80 "good ones".
One of the drivers for sorting them in the first place was that when I checked the weights, I would always find samples that you could only describe as way out of family with the batch. (More than 4 sigma away from the average.)
I used to keep them sorted out and marked them as fouling rounds. These cases were off the ends of the curve by more than 3 grains and were always found with wall thickness runouts above 0.002".

Eric K
01-13-2013, 12:32 PM
VT52

I started competing in 1000 yard BR last year. So my methodology is to reduce verticle to the least amount possible. My first test was to shoot weight sorted brass to determine if I can reduce ES. My conclusion to the test is the weight of each case is a small percentage of ES. Powder type, primers, seating depth, ambient temperature and a host of other ever changing variables can wreck your day. I am with Joe S. and FBecigneul I want everything as perfect as I can make it.

Eric K.

VT52
01-14-2013, 03:01 AM
Would it not be more meaningful to measure inside case volume using water for this reason and measuring wall thickness for any deviation? Just weighing the brass and sorting by weight, when you don't know where that weight is, is kind of taking a lucky guess. I can imagine a case weighing the same but having a thin part and a bump somewhere where as the other case would be constant all around.

Just trying to find out the real-world benefit of weighing cases to the extreme. The point not being that it is quick to do and having piece of mind, but if there is a real tangible effect at the 0.1gr level.

JRB
01-14-2013, 05:11 AM
VT52
I have been thinking about this for a while now. Being more of a tinkerer than an avid competitor
I do not shoot competition point blank, only the odd club shoot, but i do have a range at home so that helps not having to drive across state.
just making up 100 new lapua cases for my new 6PPC barrel
What i am in the process of doing and am open to criticism here.
sort by weight and mark the cases with marker pen
neck turn to thickness .270" neck so .2675"
polish neck with steel wool
uniform primer pocket, check for burrs on the inside
form a false shoulder and fireform in slave barrel with hornady butter, to give the best uniform lenght and reduce case stretch
trim to lenght
weigh again and batch into 0.5gn lots
Have not got it completed so still keen to see any weight changes occur.
JRB

mike in co
01-14-2013, 10:19 AM
kind of silly to weigh BEFORE brass prep.
trim to lenght does not affect effective case volume( volume below the base of the bullet), but does affect weight
neck turning does not affect case volume, but does affect weight.
primer pocket uniforming does not affect case volume( you seat the primer to the bottom of the pocket), but does affect weight.
now deburing the inner flash hole can affect case volume..but with lapua in 220 russian...very minor.

so prep then sort

you want one more sort.....???

load them all the same..this requires a lab scale, because the "close enough" of a beam or thrown charge will not cut it.

shoot in whatever string length you want..10 15.25....mark all cases that shoot OUTSIDE the mean group...use them for foulers......

mike in co

VT52
01-14-2013, 02:31 PM
That may work at short range, but at long-range I would end up with zero cases in a few trips to the range :cool:

mike in co
01-14-2013, 03:31 PM
lol...i agree...



That may work at short range, but at long-range I would end up with zero cases in a few trips to the range :cool:

JRB
01-14-2013, 06:25 PM
Mike, my 'madness' for weighing, before i started was to see if, in this case, if there was any changes in lots after the prep was completed.
You must 'speculate' which promted this experiment for me, that removing material in varing amounts from case to case, and therefore weight must ultimately effect case volume if all cases are infact uniform in every way. Unless of corse the brass varies in quality or composition, which we can rule out with the top few brass manufacturers.
My prevoius method has been as follows, happy for comment and advise
New lapua brass get 'double' what you need than weigh into two groups to split the pack, put aside any with more than 1.5 grain difference from the group for foulers and setting up etc. Share with a mate or put away for later the other half.
Do all the required prep than fire form and trim, work up a load and shoot
I have tried the cull method as you explain but not been able to repeat the results, most probably because i do not understand the process and effect.

I really like your method to cull brass, simple and effective for point blank shooting.
Can you tell us more about the peramiters you use, and whether cases get a second chance etc?
JRB

mike in co
01-14-2013, 06:26 PM
francis,
the problem i see is the open comments...non br shooters...

they are not using lapua or the like...
they are using winchester and rem and they can infact benefit from weight sorting that stuff...


mike in co

JRB
01-14-2013, 06:38 PM
Ok, so what i am seeing, if i get it right.

Top quality brass does not reqire any more sorting than just shoot it and cull?
This really helps us guys, that cannot get to the big matches and learn more.
If you guys are happy to share your brass culling method i am all ears.
regards
JRB

JRB
01-14-2013, 06:44 PM
VT52 when your shooting 1000 yards everything makes a difference, try weighing primers also, there can be a big difference. At 100- 200 not so much! Remember for every action there is a reaction in loading. One thing at a time so you know what done what.

Joe Salt

Joe, I guess you are looking for more than just material weight?
what is the variable? what effect does this have low or high on bullet impact
what improvements have you seen at your distance? by sorting
What perameters do you use?
regards
Jim

amamnn
01-20-2013, 09:01 PM
Someone I trust once told me that a variation of 5% or more in the weight of a batch of cases or bullets indicated that a lot of culling was needed--and/or the lot might not be a good one. I took this to mean that a tolerance of 2.5% +/- was the borderline. It seems to work. I'm talking about 100 to 300 yards since this is not the long range section of the forum.

VT52
01-22-2013, 06:21 AM
5% is a lot.

mike in co
01-22-2013, 01:33 PM
THE PROBELM WITH THIS IS THAT SOMEONE WOULD DO THE TEST AND CLAIM YOU WERE RIGHT......
but they would have done the powder with a thrower or a scale that is not precise, and the entire "test' was stupid do due to lack of precision.

mike in co

You're right! I think the whole weighing brass thing (in short range benchrest) is a thowback to earlier days when the quality control was not as good as it is now. Even when I did weigh - I never saw anything more than 0.5-1% difference in weight, and this was out-of-the box and unprocessed. Of course if you obsess and group them by tenths (0.1gr) you can drive yourself nuts sorting them into different piles. Someone needs to make up three sets of five cases with five "light" ones, five "mean or average" ones, and five "heavy" ones and using all the same components, shoot some groups and see what happens. My prediction is there won't be enough difference between the results to measure. Of course, I could be wrong but will have to be proved so to change my mind.

Boyd Allen
01-22-2013, 03:13 PM
As we all know, there are a number of factors that affect uniformity of internal ballistics. It seems to me that as a practical matter we need to determine their relative importance. Unfortunately, this is not all that easy to do. Giving the constraints of time and money, most of us make the best guesses that we can, and carry on.

To test this particular thing, I think that several sets of cases would be needed, grouped by weight, and annealed (stress relieved?) so as to have more uniform bullet pull. Using weighed charges, and a chronograph, one should be able to correlate weight variation to velocity. Does anyone know of such a test?

The only one that I can think of was rather elaborately done, by the publisher of a reloading manual, to put some real numbers on the effects that changing components in a 150 gr. bullet 30-06 load. There were a series of tests done, with a pressure gun, where one component of the load was changed, and the rest were not. I wish that I could find the test. I may have thrown the manual out because I have so many, and the binding failed. In any case, one of the tests involved different brands of cases. It listed their weights, and the pressure produced with the same bullet, seating depth, powder charge, and primer. It was an interesting article. Perhaps one of you has a copy and can direct me to the source.

alinwa
01-22-2013, 04:57 PM
Ok, so what i am seeing, if i get it right.

Top quality brass does not reqire any more sorting than just shoot it and cull?
This really helps us guys, that cannot get to the big matches and learn more.
If you guys are happy to share your brass culling method i am all ears.
regards
JRB

you really wanna' cull brass in a meaningful way? Chamber your guns .007 oversized at the base and look at the cases after fireforming and running thru a fitted sizer die. Keep those cases which show a concentric ring at the base.

13368

alinwa
01-22-2013, 04:59 PM
Ok, so what i am seeing, if i get it right.

Top quality brass does not reqire any more sorting than just shoot it and cull?
This really helps us guys, that cannot get to the big matches and learn more.
If you guys are happy to share your brass culling method i am all ears.
regards
JRB

you really wanna' cull brass in a meaningful way? Chamber your guns .007 oversized at the base and look at the cases after fireforming and running thru a fitted sizer die. Keep those cases which show a concentric ring at the base.

13368


throw out those which aren't concentric

13369

JRB
01-22-2013, 09:41 PM
THE PROBELM WITH THIS IS THAT SOMEONE WOULD DO THE TEST AND CLAIM YOU WERE RIGHT......
but they would have done the powder with a thrower or a scale that is not precise, and the entire "test' was stupid do due to lack of precision.

mike in co

Mike , a very valid point.
Why not see if three different people can contribute there time and efforts to this trial?
Do you know of anyone who would qualify and have time to help out?
it may not matter if the results where in-conclusive? but we would have some data, and a system worked out to test these perameters?
Jim

JRB
01-22-2013, 10:04 PM
Some really good discussion here, thanks all for sharing!

Alinwa, Thanks for your explaination on the case base, something i had noticed, but not thought about in any detail.
Correct me if i am wrong, i am thinking a variation in brass thickness around the base has caused this inconsistancy, so will have a more dramatic effect on case volume?

Many years back i had formed some 220 Ackley cases, and had this in lots of the formed cases, also the case base head was not concentric with the base?
We later found out the reamer i bought, was over size, and had it recut, so never really knew the true cause of the problem.

Do you have any culled cases to see if they are in fact heavier or lighter in weight to your batch? i guess this will be hard if the other cases have been trimmed etc.
Thanks again
Jim

alinwa
01-23-2013, 11:21 AM
I find the entire concept of culling by weight to be flawed. I've culled by weight, volume, "runout" and concentricity. I now concentrate on concentricity.

Boyd Allen
01-23-2013, 11:36 AM
I think that it is amusing that someone would worry about getting weight of powder so close that he believes that a single kernel of powder matters, and then discount the need to sort brass by weight, since it is the combination of powder charge weight and case volume that produces a given level of pressure. I hasten to add that I do neither, having once read Dick Wright''s description of how Dwight Scott sorts .220 Russian brass for his 6PPC (opens box, takes case out), but then not all brass is as good as Lapua .220 Russian, and I understand that for competition at longer ranges puts more of a premium on uniform velocities than does that at 1-200 yd. For this short range stuff, using thin necks, and a powder that seems to need all the bullet pull that is available, IMO sorting by seating force is much more important, and I do.

alinwa
01-23-2013, 04:25 PM
I think that it is amusing that someone who's never managed to achieve single digit ES would bother with an opinion!

Find loads that consistently stay under 10fps Extreme Spread, THEN tell us all what's important eh! ;)

(Ohh, and puhLEEEZE! don't tell us all how "it's not important, "thrown charges win" etc etc etc")

The subject here IS culling/trimming/uniforming/whatever in the interest of consistancy,

isn't it?

LOL

al

JRB
01-23-2013, 05:45 PM
Alinwa,
Just so i do not miss the point,
Are you referring to culling brass by varaition in wall thickness, with a neat little test to show up any inconsistancy?
Or culling by how well the brass formed, in a concentric fashion, as in true and concentric with the bore?
If some of your culled cases where test fired, would you expect to see a greater than normal ES?
Do you later cull cases in ES alone?
Regards
Jim

Boyd Allen
01-23-2013, 06:06 PM
Al,
I am curious about the details of your under 10 FPS ES ammo. What caliber was it, what brand was the brass, and how much did the weights of the cases vary? It may be there is a weight tolerance that they fell within, and that information would be useful as a guide. If your brass was of high quality, and very uniform to begin with, then I can see where weight sorting would not have gained you anything, but for those who are dealing with less perfect brass, with a wider spread of weights it might. Every thing that I have experienced tells me that if there are significant differences in case capacity, that pressures and velocities will vary accordingly. Surely you do not disagree with this point.
Boyd

alinwa
01-23-2013, 07:27 PM
Simply put, once I started weighing charges TO THE KERNEL OF POWDER, all this other stuff just faded into insignificance. After YEARS of buying and using every gadget and trick from every book, magazine and forum on God's Earth............the light came on.

You name the tool, I've got it.

You name the test, I've tested it.

You name the gimmick, I've tried it.

AND.....I weigh, or have weighed in testing, charges from 26gr (PPC/BR etc) to 126gr (blown out super magnums)

I will say this, that IF YOU WANT CONSISTENT VELOCITIES you must weigh charges scrupulously.

I AM NOT SAYING that everyone needs to weigh charges to achieve their standard of accuracy, BUT IF.....

Now, there are a bunch of other things to do once this goal is achieved, ways to alter group size and shape, often the same methods used for UN-weighed charges....for instance neck tension WILL change the shape of groups in highly accurate rifle systems..... but I think this completely misses the intent of the OP.

On the subject of neck tension. It is further my opinion that "you're fooling yourself!" if you think neck tension has any effect on rifles incapable of tenth minute accuracy. And I do mean ANY EFFECT, taking into effect the "every little bit helps" idea and it's corollary "it all adds up," I'm saying neck tension does NOTHING for a 1/2 minute rifle system. And a 1/2 minute rifle system is already a full-blown custom. Not "BR" but definitely not a factory rifle. IMO neck tension adjustment as a useful tool applies only to BR rifles.

I am furthermore NOT SAYING that weighed charges are "necessary for accuracy" in all cases. But I will say that in some instances, like 1K shooting, it is my opinion that you'll chase your tail forever NOT weighing charges.

And all this other stuff just clouds the issue. Or at least it did for me, for 20yrs :)

opinionsby

al

Keith Skjerdal
01-23-2013, 07:29 PM
I currently shoot a 6-250 IMP 30 degree, 6BR, Win 284 and a 308 at LR in Fclass. I have a little case in 22 cal for coyotes that is a real pain to make cases for. I have shoot a ton of HBR with 308s and 30*47 and LV/HV with 6PPCs and 6BRs.

For my LR FO Win 284, I use WINCHESTER brass. Too cheap to buy Lapua 6.5*284, plus it may make the necks too thin after expanding (running tight necked 284 Win with a .312 NK) and the way I see it, once you do all the prep, does not matter much who's brass you start with??

I do all the prep work first ... ultrasonic clean, dry, trim to 2.160, cull shorter aside, light cut primer pockets, inside flash hole deburr only removing any lumps, FL resize (possible to lose some there too, not all always fit in the shell holder), anneal(easier to turn, coming up), mandrel up, outside neck turn to .0125, do another ultrasonic and dry, blowing out pockets and inside of cases with air compressor around 60 psi

to 300-600 cases, then weight sort em to the tenth and none get culled from this point. The few super light and heavies went into a test box of maybe 10-20 rounds. The large bell/population went into a lot (many boxes of 50 or 60) and that is what I shoot. Each box is still weight sorted, so you may have 15 cases at 204.2 then 7 at 204.3 etc. Most boxes are under .5g from case 1 to case 50 and a few boxes are within .2g, like 25 at 203.9 and 25 at 204.0

Does it make a difference??? DONTKNOW I think I did once test some cases from one extreme to the other in one of my guns, and yes, there was a POI change, but not much velocity change from what I remember. I have yet to test that test box of 10-20 284's either! Don't want to burn up my good barrel testing all the time :) But I do use freshly prep'd brass at the big matches and load nightly in my room one or two boxes...

But what else are r u to do in Canada at -20 to -40 for two months, MAKE BRASS LOL.

Only problem, all that hand brass work over the years and over many wildcats, has given me issues with trigger finger(Trigger finger limits finger movement. When you try to straighten your finger, it will lock or catch before popping out straight.
Trigger finger is a condition that affects the tendons in your fingers or thumb.). Got it bad now in my thumb LOL. Even have to wear a brace now 24/7 for a few wks or until it gets better, which better happen since I'm heading to Sac for the AMCAN... plus, a word from the now wise, USE POWER TOOLS all you can, avoid excessive pressure on those fingers all you can!

alinwa
01-23-2013, 07:32 PM
Alinwa,
Just so i do not miss the point,
Are you referring to culling brass by varaition in wall thickness, with a neat little test to show up any inconsistancy?
Or culling by how well the brass formed, in a concentric fashion, as in true and concentric with the bore?
If some of your culled cases where test fired, would you expect to see a greater than normal ES?
Do you later cull cases in ES alone?
Regards
Jim

I cull brass for uniformity of SHAPE, not capacity. Eccentric brass doesn't size right. It "bananas."

IMO crooked brass throws shots due to it screwing with the vibration cycle of the system.

Yes, I've "indexed cases."

al

alinwa
01-23-2013, 07:36 PM
Al,
I am curious about the details of your under 10 FPS ES ammo. What caliber was it, what brand was the brass, and how much did the weights of the cases vary? It may be there is a weight tolerance that they fell within, and that information would be useful as a guide. If your brass was of high quality, and very uniform to begin with, then I can see where weight sorting would not have gained you anything, but for those who are dealing with less perfect brass, with a wider spread of weights it might. Every thing that I have experienced tells me that if there are significant differences in case capacity, that pressures and velocities will vary accordingly. Surely you do not disagree with this point.
Boyd

Well, yesssss, I hesitantly disagree. I've not yet had to cull cases by volume while weighing charges. I have no idea'r what my weight variation is since I achieve my goals without checking it. Yup, I've got pages of bell curves and boxes of segregated cases and bullets (and juenke'd and length-sorted bullets, and se)

Win, Lapua and Norma brass cases from 6PPC to 338L.

al

JRB
01-27-2013, 06:43 AM
Al, Thanks for your help and clarification with this.
Just a quick one, do you form your cases dry? or with a lube of sorts?
What variation do you get in case lenght after forming?
Regards
Jim

alinwa
01-27-2013, 11:33 AM
Al, Thanks for your help and clarification with this.
Just a quick one, do you form your cases dry? or with a lube of sorts?
What variation do you get in case lenght after forming?
Regards
Jim

You'll have to be more specific re "form cases."

Do you mean initial form? Fire form? Maintainance form? lube in the die? The chamber? what???? It takes several firings to get my brass where I want it altho the first firing "for real" can occur right after fire form since at that point it fits almost perfectly. My case variance after initial ff is under a half-thou everywhere except the casemouth which may (will) need to be trimmed depending on the amount of blowout performed during initial ff.

hth

al

Boyd Allen
01-27-2013, 07:03 PM
Very much related to Al's case shape thing.. another good read from German Salazar:
http://riflemansjournal.blogspot.com/2009/07/reloading-audette-neco-case-checker.html

VT52
01-28-2013, 04:24 AM
Boyd, the question, or remark, was that due to density differences between brass and powder/air you are talking about fractions of a single kernel of powder. My point was also that you don't know where that weight difference is and if it even affects case volume.

JRB
01-28-2013, 05:49 AM
You'll have to be more specific re "form cases."

Do you mean initial form? Fire form? Maintainance form? lube in the die? The chamber? what???? It takes several firings to get my brass where I want it altho the first firing "for real" can occur right after fire form since at that point it fits almost perfectly. My case variance after initial ff is under a half-thou everywhere except the casemouth which may (will) need to be trimmed depending on the amount of blowout performed during initial ff.

hth

al

Al,
My appologies for not being more specific.
My question relates to the initial 'form' from a .220 russian case, to the PPC chamber?
Do you aid the forming in any way, with lube or the like, applied to the case neck and shoulder, just prior to firing, to give more consistant forming results?
Regards
Jim

alinwa
01-29-2013, 02:53 AM
Al,
My appologies for not being more specific.
My question relates to the initial 'form' from a .220 russian case, to the PPC chamber?
Do you aid the forming in any way, with lube or the like, applied to the case neck and shoulder, just prior to firing, to give more consistant forming results?
Regards
Jim

In this regard, NO, I do not lube my chamber, ever, and doing so gives me less consistent results than what I do. IMO it's a terrible bandaid fix for the problem of excessive headspace.

mike in co
01-29-2013, 06:01 AM
but not true in quality brass...
if the length is the same, the outside size the same, the primer pocket uniformed anf the flash hole depurred, then the excess brass from excess wieght is on the INSIDE of the case, so the interal vol is diff.......
yes there is one known case where extractor grooves were not uniform...ONE KNOWN CASE.

THE ENTIRE ISSUE WITH THIS QUESTIONS is "what quality of brass are we talking about ?"..lapua norma rws..my comment stands..win rem ..who cares??

mike in co


Boyd, the question, or remark, was that due to density differences between brass and powder/air you are talking about fractions of a single kernel of powder. My point was also that you don't know where that weight difference is and if it even affects case volume.

mike in co
01-29-2013, 06:04 AM
i weigh all my brass....
typically 50 lbs to the 5 gal bucket when i buy or sell in bulk.....
retail sales are weighed into 100/500 count bags....
wholesale caliber specific is still by weight, but by the 1000 count multiples.
very uniform...

mike in co

Andy Cross
01-29-2013, 05:47 PM
Maybe interesting for some folks, old news for others... Someone at the club asked why people weigh brass and I looked up some figures to try to explain a little about the sense, or non-sense, for doing this (not just for BR, for plane-jane rec shooters as well).



Brass = 8400 kg/m3

Air = 1.29 kg/m3

Vihta N133 = 870 kg/m3


1 grain of brass displaces 1.29/8400 = 0.000153 grains of air

1 grain of brass displaces 870/8400 = 0.965 grains of powder

1 kernel of N133 weighs around 0.025grs

So 1 grain in case weight gives the same result as 0.1gr of powder (in terms of volume, not weight), ie 3-4 kernels of N133.


Depending on what you shoot (BR, plinking, high-power), that 0.1gr powder volume difference may mean nothing, or it may mean something. I can not, however (imho), see how sorting at the 0.1gr level of brass weight would mean anything, besides on paper, to real world results, as this would mean 0.01gr less volume for the powder.

A few years back my farther built a .243 win and although it was a field rifle it was essentially a HV rifle built on a trued and sleeved Rem 700. One batch of Federal nickel brass weighed 15gn thats not a typo more than the last lot of Rem brass he was replacing. It did significantly alter the maximum load and other aspects of the loads accuracy. But I gave up weighing my PPC brass for short range BR because the heavy brass as in plus or minus 2gn didn't seem to produce any flyers.
Andy

alinwa
01-29-2013, 11:38 PM
A few years back my farther built a .243 win and although it was a field rifle it was essentially a HV rifle built on a trued and sleeved Rem 700. One batch of Federal nickel brass weighed 15gn thats not a typo more than the last lot of Rem brass he was replacing. It did significantly alter the maximum load and other aspects of the loads accuracy. But I gave up weighing my PPC brass for short range BR because the heavy brass as in plus or minus 2gn didn't seem to produce any flyers.
Andy


That's not at all odd. I've got cases here in three different chamberings (one a PPC) where if you inadvertently used the wrong BRAND of case you'd be sawing your barrel off.