The NUT behind the trigger remains the biggest factor ... just saying! 
gun)
gun)
weight sorting brass, Now what?
- Thread starter elkhntr
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J E Custom
Well-Known Member
Good point, But there is a method to my madness.
The reason I size, trim and de-burr is to get the brass as close to the same outside dimension
and as uniform possible so the inside will better indicate the volume (New brass is seldom uniform
dimensionally).
The Lapua brass is very close and sorting is normally confined to 1 or 2 batches. (This brass is
good enough to skip weight sorting If a person doesn't want to spend the time).
As I stated early on , it also helps indicate the brass quality. I have weight sorted some brands
and ended up with 8 to 10 batches and some that were to far out to use them. (I know longer
buy these brands unless I am desperate).
J E CUSTOM
MagnumManiac
Well-Known Member
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I have to ask, what cartridge are you weight sorting?
I have only sorted 300WM, 300RUM and 264WM. The 300RUM is used for 338 Edge.
I do the same as you, except I don't trim and I fireform my comp brass and keep it in batches that cover a match +20, just in case.
Even though I believe weight sorting has no bearing on case volume, unless actually checked, as a case gets SMALLER, case capacity uniformity becomes far more important than large cases.
I have a 338-416 Rigby in development using Norma brass, I can't detect any discrepency in capacity, on a test lot of 30 out of 200 pieces, using my burrette.
The weighed cases differ by 3-5gr on average, yet, I cannot detect much difference in cc's. I haven't used this rifle yet, it's not finished, but think it should be more uniform than my 338 Edge, which is now almost impossible to get brass for here.
I guess, we will see.
Cheers.
gun)
J E Custom
Well-Known Member
I weight sort all rifle brass and feel it is worth the effort because when I first started to do this , I was trying to figure what was causing the occasional flyer.
I came up with many reasons and set out to eliminate all of them if I could. case volume was just one of the reasons. Neck tension, case OAL length differences, work hardened brass (To many shots before I annealed them), Improper sizing (Not consistent), not loaded concentric (Bullet and cases had to much run out), Differences in case wall thicknesses, Bullet weight differences, Bullet diameter differences, ETC.
I then set out to see what was the best method to test/compare volume. I tried using ball powder,
de mineralized water with a wetting agent and these methods proved to me that the brass has to be prepared as identical on the outside as possible to be consistent. some cases had different depths of
extractor groves and different case head thicknesses. (This is the reason I feel that brass should be
kept in batches/lot numbers even if you don't weight sort). When I prepped brass from a single lot I found poor quality control in some brands as stated earlier and no longer buy those brands if I can avoid them.
The reason that I weight sort is because it is as accurate as the other methods but is much faster
and produces the same results.
Note: In my opinion if everything else is not done to get the best consistence weight sorting or volume testing is a waste of time. In many cases loading random/mixed cases produced good results, but when all the steps mentioned were used accuracy was improved, some times by very little but in some, it was improved drastically.
If you do all of these things It will not guarantee sub 1/4 or even a 1/2 moa but it will improve the accuracy to some degree in my opinion
J E CUSTOM
Wado
Well-Known Member
I believe this is my first post on this forum so here goes. After I size, trim, clean the mouths up and flash holes I stick my brass back into the polisher for a final clean up. Put the gloves on and blow every piece of brass out with dry air to make sure there are no pieces of media in them then I weigh sort. I reach in the bucket of brass ( alike head stamps ) and grab a random piece. I set it on my digital scale and write the weight down. I may grab three or so more and record the weights to see if there is a average weight to start with, once I decide which way I want to go high or low I set that piece of brass on the scale then zero it. Then I just weigh one at a time and the overs go into one pile and the under into another. I usually separate them four ways. Does it help, I doubt it but it doesn't take all day to do.
I weight sort and have found a correlation between case weight and case volume in brass fired in my chamber. Water volume sorting of virgin brass is a waste of time. They are made on multiple machines and have different external dimensions, usually in shoulder length and body diameter. Naturally they will have different internal volumes. Water test fired brass and you'll see a pretty close relationship to case weight.
Why is this important? ES. Case volume affects pressure. Variable pressure increases ES. Second, heavier cases have thicker necks. Thicker necks increase neck tension. Variable neck tension increases ES.
But sorting 308 brass into half-grain lots for hunting purposes is too anal. Do three grain lots instead. That's how Lapua does it. That's how ATK does it with M118LR sniper ammo.
Why is this important? ES. Case volume affects pressure. Variable pressure increases ES. Second, heavier cases have thicker necks. Thicker necks increase neck tension. Variable neck tension increases ES.
But sorting 308 brass into half-grain lots for hunting purposes is too anal. Do three grain lots instead. That's how Lapua does it. That's how ATK does it with M118LR sniper ammo.
