Weight of brass differences

[1Shirt]

Well, the temp is below zero, winds still blowing, and forcast is for around 20 below tonight, so the brass monkey is inside, and have time to do a few things I have been putting off for a long time.

One day last summer I picked up 65 apparently once fired federal 223 Rem brass at the range. Head stamps all appear to be the same, but don't know that for sure. Anyhow, I sat down this a.m. and seperated them by weight on an electronic scale and came up with the following weight variations. (did not deprime or resize the brass)

Weight--# Weight--# Weight--# Weight--# Weight--#
93.2 4 93.8 11 94.0 7 94.2 6 94.4 3

94.6 2 94.8 1 95.0 1 95.8 1 96.8 1

97.2 7 97.4 3 97.6 3 97.8 5 98.0 3

98.4 3 98.6 1 99.0 2 99.2 1

This is not by any means scientific or analytical, but to me it was eye opening. I just bought 50 new 375H&H Rem Brass, and 50 new 243 Win Brass, and will do a weight comparison on these as well. Doubt that a grain or two would make much difference accuracy in large capacity cases like 375, but think it must have appreciable variability accuracy in smaller cases, and in particular with the small cases like 223. I weigh my 30 cal cast boolits to within .3 of a grain, and weigh and seperate 22's and 6mm's to .1grain.

Intend to load the above cases with my pet loads for cast and see if I can come up with something that resembles a logical conclusion regarding accruacy. This may seem anal of me, and admittedly this is range brass, but there are a lot who shoot range brass, and I know I have in the past been the brass by seperating only by headstamp and Mfg.

A 6 grain variation in a case as small as 223 to me it seems must be an internal case space factor, and must rusult in vol variance, and accuracy potential. Wonder if anybody else has done a like comparison.

Well, guess I will go weigh the new brass!
1Shirt!:coffee:

[dubber123]

Try 10+ grains difference in .38 Special. I have found the same in .357 Mag. That can make a BIG difference if it's a top end load to start with.

[sundog]

Yeppers, I've weighed .223 cases also, and segregated them for accuracy testing. If you really want an eye opener, weigh some Hornady head stamps. The batch of them that I have are very heavy, enough so that they are segregated out into their own batch.

As far as the others of same head stamp and same weight, they were also outside neck turned for a bolt gun. Did it make any difference? I think so, and since I am the onliest one I need to please, other than Mrs Sundog, I doubt anyone will convince me that all that work is not necessary.

[mike in co]

I AM A BELIEVER IN WEIGHT SORTING

having said that i do not know if in a low pressure cast boolit load it would matter.


i still do it....

[C.F.Plinker]

I did a similar test, although on a smaller scale, several years ago and found the the water capacity for cases having the same weight could vary from 0.3 to 0.5 grains depending upon the manufacturer of the case. Similarly, cases having the same capacity could vary in weight up to 1.5 grains. Half of the cases were once fired in my AR and the others, like yours, were range pickups. The above numbers were from unsized and untrimmed cases. I then sized and trimmed 10 of the WCC cases that were fired in my rifle. Cases having the same weight had a capacity difference of 0.1 grains and those holding the same amount had an empty weight difference of up to 0.6 grains. I would be interested in knowing what the variance in capacity of your cases is.

[1Shirt]

As a follow up I just weighed 51 new 3757&H cases. (51 because that was what was in the bag of new Rem brass). I had inside deburred the flasholes, and run them over a lee trimmer. ( most right on the button, and very few had just a little bit of bright on the end from the cutter) (on the other hand, in the process of deburring the flashole, over half of them had little bits of brass drop out). Anyhow, the low for the 51 cases was 248.2 gr. and the high was 250.4 which shows only a 2.2 variance in weight for these big cases. That impressed me! Was going to do the new 243, but forgot I loaded them last week. You know, ya, memory is the second thing to go!

Wow, 10 gr. difference in 38 and 357 brass. Now I will have to do some serious weighing of these as well.

CF, have never messed with water capacity and cases, and would be interested in just exactly how you did it so that I would be able to do a comparison.

Mike in Co, don't know either regarding cast, however tend to think that logic would dictate that the more consistancy you have in loading in weights of all components, the higher the probability of the best accuracy.

I do know that as I have the time to do the weighing will do so. Now as soon as I can get some of these 223's loaded, and it is anyware near warm enough to shoot, will see if size of group and or point of aim varies with different case weight.

1Shirt!:coffeecom

[dubber123]

In 45 LC, switching from my lot of RP brass to Federal required me to reduce my powder charge by 1.5 grains to get the same velocity...

[helg]

Some crazy benchresters sort their brass by water capacity in grains. This is even more time consuming than weighting the fired brass. The brass to measure obviously has to be uniformed. It can be either all fired from the same gun, or all sized by the same die. For internal ballistics calculations QuickLoad recommends measuring rifle brass after firing from the gun that is it intended to be fired, before sizing. If you just want to sort the brass, it should not matter whether it is all fired from your gun or all sized in your die.

[mike in co]

Some crazy benchresters sort their brass by water capacity in grains. This is even more time consuming than weighting the fired brass. The brass to measure obviously has to be uniformed. It can be either all fired from the same gun, or all sized by the same die. For internal ballistics calculations QuickLoad recommends measuring rifle brass after firing from the gun that is it intended to be fired, before sizing. If you just want to sort the brass, it should not matter whether it is all fired from your gun or all sized in your die.


actually i'm one of those...but most br shooters either shoot them out of the box or buy weight sorted brass( that being 6ppc......they still have to fireform them)

for my 223 br gun i have a small lot of 30 pc of brass , that when fulley prepped weighed the same, and have the same internal volume.

there is some discussion that since the brass sizes to chamber size so quickly that measuring fired brass is more valid than sized....minor issue.
this is allin the short game...100/200. i am building a 1000yd gun and just went with weight sorting fully prepped brass.

for cast boolits i normally will go with a plus or minus 0.5 or so for fifty/sixty pcs of brass.
to be able to really measure the weight of the brass at plus or minus 0.1 you need a scale that measures to less than that. i use a denver scale mx123....+/- 0.02 with .03 sensitivity.
mike in co

[C.F.Plinker]

1shirt - to find the case capacity I leave the fired primer in of course, weigh the case empty, fill it with water to the mouth, and weigh it again. The difference in weights is the gross capacity in grains of water. I fill it with a water dropper that is large enough to hold all of the water needed to fill the case squirting it in slow enough that bubbles can't form within the case. When I'm done filling I want a meniscus (curvature of the water due to surface tension) that is above the case mouth. I have a fluorescent light above my bench and I look for its reflection in the top surface of the water. I then use the edge of a tissue or paper towel to absorb a little of the water. When the reflection is flat, the case is full (not overfull or underfull) and I record the weight of the full case. Since I am using a digital scale, I lift the full case off and make sure the scale goes back to zero. If it doesn't I rezero the scale and then reweigh the still full case. Hope this helps.

[1Shirt]

Any day that something new is not learned is a day wasted. Have learned quite a bit from the responses to my thread. Hope to keep on learning for many years. Now to try some of the learnings and test some things with old eyes on the range. Thanks guys!
1Shirt!:coffee: