Sorting Brass by Weight

[Bill2905]

I have never done any sorting of brass before but am interested in learning more about it as a method for increasing case uniformity.

I have two boxes of new Lapua 6BR cases with different mfg lot numbers on them. It was a slow night here so I weighed 25 pieces from each box with the following results;

Lot A
Average = 128.6 gr
STDEV = 0.35

Lot B
Average = 128.7 gr
STDEV = 0.51

My understanding is that it is a common practice to determine the average weight and then select all the cases that fall within +/- X and exclude all those that do not.

For the weights shown above, what is a reasonable tolerance to set for culling the outliers?

Thanks

[Robinhood]

I like to get rid of the ones that are way off. At a half a grain you are not doing to bad. I mark the ones that are outside of the average. If it shoots good in my group I know that I am in the optimal weight charge and feel good about the sorting. If it is a flyer it is culled as a suspect. I do my groups at 400 and test again at 600.

In my opinion you will get the best mileage from even neck tension, Bullet RO under .002" above the ogive and Very close and accurate powder charges(.03 grain variation)

[mikeinco]

what distance ARE YOU PLANNING TO SHOOT AND WHAT ACCURACY ARE YOU EXPECTING.
i have sorted as fine as .05. i have sorted to less than 0.1cc in volume sort,
BUT nothing maters is ALL the parts aren't at the same level.
0.1 sort and then combine in small shootable groups.......seldom bigger than +/- 0.3, typically +/- 0.1.
define the task, list the tools then see what helps to the goal.
( my personal lapua 6br brass is sorted to a .25 SPREAD. used in 6br, 30 br and 6 dasher)

[Ted_Feasel]

I have never done any sorting of brass before but am interested in learning more about it as a method for increasing case uniformity.

I have two boxes of new Lapua 6BR cases with different mfg lot numbers on them. It was a slow night here so I weighed 25 pieces from each box with the following results;

Lot A
Average = 128.6 gr
STDEV = 0.35

Lot B
Average = 128.7 gr
STDEV = 0.51

My understanding is that it is a common practice to determine the average weight and then select all the cases that fall within +/- X and exclude all those that do not.

For the weights shown above, what is a reasonable tolerance to set for culling the outliers?

ThanksOn any brass its preferable to by lot then what i do is trim, pocket uniform,.flash uniform, deburr and etc and then weigh it and check volume. I found if you prep it first you will have alot more cases with acceptable tolerance. Thats just my method.. im sure there are those here that agree and disagree. My reasoning is even lapua has length and pocket depth variations so if I make those all the same it brings my tolerances closer. I trim to CIP standards which minimum on 308 is 2.001 where saami is 2.005. I uniform pocket depth to .1300 since the typical range seems to be .1294-.1297... so .1300 gives me a manageable equal depth. Im sure I could go up to .1299 and maybe .1298. .1250 is min, .1320 is max. Give that a try and I bet you'll get alot more cases that are closer to identical

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[Fuj']

I sort my brass to a .25 spread. Any out of the norm, along with out
of spec bullets go into my fouler box. I have a separate small Peregrine
scale that measures to one hundredth of a grain. It don't take long.

[mikeinco]

prep first is a big clue
trim to length removes weight but not effective volume
primer pocket uniform removes weight, not effective volume BUT i have seen pockets move after firing so i do it after firing,
neck turning removes weight, not volume change
inside flash hole deburr...minor vol change with weight change.
just depends in the original goal.
if none of those steps are in you plan, a basic weight sort is still better than none

[Bill2905]

Thank you for all the suggestions. I encountered a handful that were outside of +/- 1.0 grain so those certainly need to be culled. I think I'll start at +/- 0.5 grain and see how many get pulled. Like most things new, I start to get a feel for it once I get some experience under my belt.

[Robinhood]

On any brass its preferable to by lot then what i do is trim, pocket uniform,.flash uniform, deburr and etc and then weigh it and check volume. I found if you prep it first you will have alot more cases with acceptable tolerance. Thats just my method.. im sure there are those here that agree and disagree. My reasoning is even lapua has length and pocket depth variations so if I make those all the same it brings my tolerances closer. I trim to CIP standards which minimum on 308 is 2.001 where saami is 2.005. I uniform pocket depth to .1300 since the typical range seems to be .1294-.1297... so .1300 gives me a manageable equal depth. Im sure I could go up to .1299 and maybe .1298. .1250 is min, .1320 is max. Give that a try and I bet you'll get alot more cases that are closer to identical

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I'm impressed. Over 99 percent of the people on this planet cannot repeat measurements within .0001"

[Ted_Feasel]

I'm impressed. Over 99 percent of the people on this planet cannot repeat measurements within .0001"Yep. It makes a.difference getting a good routine and sticking to it

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[Robinhood]

How do you hold your brass while you pocket uniform Ted? What tool are you using to cut with?

[mikeinco]

in his case i would bet it is a TOOL that cuts to a fixed depth..not a measured individual depth.
i use a carbide cutter. then it quits cutting i am done( it has a shoulder to stop on).
yes i can measure to .0001 and have been doing so for over 50 years.



I'm impressed. Over 99 percent of the people on this planet cannot repeat measurements within .0001"

[mikeinco]

i know you did not ask me, i use two methods with the same cutter.
by hand with the cutter in a sinclair handle,
or
by lathe with the cutter chucked up and the brass held by hand in a wilson case holder.
specific depth is not a big issue, uniform case to case is for uniform ignition.


How do you hold your brass while you pocket uniform Ted? What tool are you using to cut with?

[Ted_Feasel]

How do you hold your brass while you pocket uniform Ted? What tool are you using to cut with?I use 21st century uniformer and case holder for my le wilson

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[Ted_Feasel]

I use 21st century uniformer and case holder for my le wilson

Sent from my SM-N975U using TapatalkI have a hornady also its just not as easy to adjust

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[Robinhood]

in his case i would bet it is a TOOL that cuts to a fixed depth..not a measured individual depth.
i use a carbide cutter. then it quits cutting i am done( it has a shoulder to stop on).
yes i can measure to .0001 and have been doing so for over 50 years.

Mike
What tool are you using that you measure primer pocket depth within a tenth?


Thanks Ted
I also use my Wilson to hold some cartridges and others that I don't have a Wilson holder for, I use one of those jar lid grippers. I was interested how others did it.

[mikeinco]

i never measure..
i only cut TILL IT STOPS on the shoulder of the tool.
never use an adjustable tool.....buy an inspect shouldered cutter....carbide

Mike
What tool are you using that you measure primer pocket depth within a tenth?


Thanks Ted
I also use my Wilson to hold some cartridges and others that I don't have a Wilson holder for, I use one of those jar lid grippers. I was interested how others did it.

[Ted_Feasel]

Mike
What tool are you using that you measure primer pocket depth within a tenth?


Thanks Ted
I also use my Wilson to hold some cartridges and others that I don't have a Wilson holder for, I use one of those jar lid grippers. I was interested how others did it.I use the small end of my mitutoyo, the end that move out as you open the calipers.. I think I spelled that right

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[mikeinco]

not an accurate tool
a real depth mic would do it, but why ??( they read to .0005 but are only accurate to .001)
use the rigtht cutter and be done.


I use the small end of my mitutoyo, the end that move out as you open the calipers.. I think I spelled that right

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[Ted_Feasel]

not an accurate tool
a real depth mic would do it, but why ??( they read to .0005 but are only accurate to .001)
use the rigtht cutter and be done.I think I got the right cutter. 21st centuries are pretty nice. The calipers are.one of best there are as far as I knew. The measure in .001 but you can pretty easily split the .001 marks. Ill probably get a depth guage eventually

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[daved20319]

I think ya'll are getting lost in the weeds, here. As a hobby machinist, I have plenty of mics and calipers, but I really don't see the need for measuring to .0001". My digital caliper reads to 4 decimal places, but I treat that 4th digit as a +/-, and round up or down to the next thousandth. Serious question, what possible difference does it make if your case length differs by a thou? Even shooting long range, I find it hard to believe it's going to matter at the target, especially with all the other variables involved. Later.

Dave