Weighing your brass question

powdergun

powdergun

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Before I ask just want to avoid beating a dead horse:

I know from what I have read
1) The relation between weight and case volume seems to spark a lot of debate.
2) This is a bigger issue for benchrest competitors and not so much for schmucks like me who like to plink out to 500 yards


My questions for you guys are:
1) Do you sort new brass by weight ?
2) What would you find as an acceptable range in weight. ( Just weighed some win brass 300wm and found a 5 grain range from lowest to highest )

My goal: Consistently hit a clay pigeon at 500 yards. My current set up is at MOA ( under a 5" group at 500yards) but getting to the point I need to start a new batch of brass. My current brass is Hornady that I did not weight sort but I was just curious if weight sorting would improve things a bit more.

Thanks in advance for all the info and advice
 
Depending on the size of the brass, I'll weigh and group them and keep/mark the outliers for fouling shots. Short action brass I can live with a 2gn variation...I don't throw away brass unless it's defective.
 
I like to get at least 500 cases, preferably 1000 new cases (same lot #) and then weigh them. It only has to be dome once, so why not?

I label a bunch of pails in either 0.3 gr increments or 0.5 gr increments and then weigh.

I then transfer the brass to 50 round boxes. the lightest and the heaviest get marker "Practice only".

Then I start at one end and transfer brass to 50 round boxes. I label inside the lid the weight of that batch.

Does it make a difference. I think it does because I think it does.
 
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I have seen 7% difference in weight between brands of brass.I've read of one with a 10% difference in the same batch, so I guess it's a good idea. I will measure neck thickness variation in every case.
 
powdergun said:
Before I ask just want to avoid beating a dead horse:

I know from what I have read
1) The relation between weight and case volume seems to spark a lot of debate.
2) This is a bigger issue for benchrest competitors and not so much for schmucks like me who like to plink out to 500 yards


My questions for you guys are:
1) Do you sort new brass by weight ?
2) What would you find as an acceptable range in weight. ( Just weighed some win brass 300wm and found a 5 grain range from lowest to highest )

My goal: Consistently hit a clay pigeon at 500 yards. My current set up is at MOA ( under a 5" group at 500yards) but getting to the point I need to start a new batch of brass. My current brass is Hornady that I did not weight sort but I was just curious if weight sorting would improve things a bit more.

Thanks in advance for all the info and advice
Click to expand...

Happy you asked. Been wondering the same.
 
I typically just buy quality brass (ADG, Lapua, etc) from the same lot # and not worry about it. Usually that results in very consistent weights. Lot to lot can have a big variation, even with good brass. Not sure how much it really matters though, so I'm curious to hear if anyone has tested this out...
 
If this is a concern, measure the case volume of fireformed brass. Weight is not a good indicator of volume because mass manf cases can have variations in the external machining... different weights but very similar volumes.

I doubt you will find enough volume variation from the same lot of brass to matter. The loads may change from batch to batch but variations in cases within the same lot is rarely a problem

Jerry

PS... if you want higher levels of accuracy, I would look at the consistency in charge weight as well as the right charge weight. Then barrel and bullet quality.
 
Mystic Precision said:
If this is a concern, measure the case volume of fireformed brass. Weight is not a good indicator of volume because mass manf cases can have variations in the external machining... different weights but very similar volumes.

I doubt you will find enough volume variation from the same lot of brass to matter. The loads may change from batch to batch but variations in cases within the same lot is rarely a problem

Jerry

PS... if you want higher levels of accuracy, I would look at the consistency in charge weight as well as the right charge weight. Then barrel and bullet quality.
Click to expand...

Great answer!
 
Another take on it by the Witch Doctor

Effects of Case Head Thickness on Ballistics and Precision
The purpose of this video is to describe the effects of case head thickness on ballistics and precision. The findings show a linear relationship between case head thickness and velocity with thinner case heads having slower velocity relative to thicker case heads. In terms of precision, the thickness that represents the average within the range of values showed the best precision. The practical implications are discussed and include case head thickness sorting in long range shooting.

https://ww.youtube.com/watch?v=VanQm9-RZxs&t=2s[/url]

Interesting but way down the rabbit for most purposes.
 
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Mystic Precision said:
If this is a concern, measure the case volume of fireformed brass. Weight is not a good indicator of volume because mass manf cases can have variations in the external machining... different weights but very similar volumes.

I doubt you will find enough volume variation from the same lot of brass to matter. The loads may change from batch to batch but variations in cases within the same lot is rarely a problem

Jerry

PS... if you want higher levels of accuracy, I would look at the consistency in charge weight as well as the right charge weight. Then barrel and bullet quality.
Click to expand...

So in the grand scheme of things, even if you are looking for relatively cutting edge accuracy, its pretty low on the list?
 
I sort my .308 Lapua brass into .5gr batches. This lot of brass ran between 170 gr to 174 gr. With most falling in the 173 gr range. Out of about 1200 pieces of brass I ended up with about 100 on the low end and about 50-60 on the higher end. Does it make a difference? In my mind, a case weighing 170 gr will have a different POI than a 174 gr case with the same powder charge at long range.
.223 brass into .3 gr batches.
 
Joel said:
So in the grand scheme of things, even if you are looking for relatively cutting edge accuracy, its pretty low on the list?
Click to expand...

If you are working with 1F range pick up, even if all the same manf, I would take the time and sort by volume. If you are cracking open a new box of quality brass, more important things in life to do.

Brass needs to be consistently prepped and of similar volume... that is as much as it can provide to your accuracy success.

Jerry
 
Most rifles won't be able to tell the difference between a few tenths of a grain in the material weight of the cases. Unless the case capacity is affecting accuracy with a tenth of a grain, which is possible with smaller cases, nothing is likely to be noticeable.

If you're going to get picky, make sure your firearm is accurate enough to go to the trouble of doing so.

When there is a large difference, especially that noticed between surplus military cases, or some European cases, such as PRIVI can be very heavy, when compared to commercial North American or other European offerings, such as Norma and Lapua.

I follow the same procedure for selecting batches of brass as Ganderite. Mostly by force of habit and I have the time to do it.

There is one step I add though. I full-length resize the case and trim all of them to the same length before doing volume comparisons.

I will do one other thing. I select a couple of cases from each weight and tape over the primer hole with one of those cheap stickers available from Staples. Then do a capacity comparison with water.

This is very easy and only takes a couple of minutes.

Weigh the case with the sticker on the bottom when it's empty. Then fill the case with water so a convex meniscus form over the case mouth and weigh it.

I add most of the water before putting the case on the scale and top it up with an eye dropper. Be careful not to overfill.

This will give you an insight into the REAL capacity of the case.

Now, to get a perspective of how much difference this makes to actual powder capacity or air space, weigh out a drop or two of water equal to the weight difference in capacity, then add the same weight of the powder you're going to use beside the water on the scale until you have doubled the weight.

The space taken up in the case by the same weight of powder on the scale will be much smaller.

The volume taken up by the powder is roughly 3-4 times that taken up by water.

When the volume of powder it takes to make up the difference in case volume, it is almost always less than a tenth of a grain, even on mid-size cases such as 308Win and 30-06, all the way up to the larger magnum cases.

As mentioned, there is definitely enough difference between some cases, depending on the specs they were manufactured to. The smaller the case capacity, the more difference the result will be concerning pressures created with the same powder charge and primers if the cases get mixed into the same batch.

Some folks separate cases by manufacturer. This can be an issue, but rarely.

Governments can afford to pay extra for a half dozen grains of material in the cartridge cases they order for their firearms, which will have varying chamber dimension specs. They load accordingly, usually with proprietary powders and primers for safety reasons, especially on full auto firearms.
 
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If you think it helps, or if you don't think it helps, you are right. Having said that- I also follow Ganderite's process (although nowhere near the volumes he is doing). Buy new brass, sort into 50-ct boxes. try to figure out the other reasons things aren't just going as well as expected. The only true measurement is to do the case capacity on fired brass- but I draw the line somewhere.
 
Jon87 said:
I typically just buy quality brass (ADG, Lapua, etc) from the same lot # and not worry about it. Usually that results in very consistent weights. Lot to lot can have a big variation, even with good brass. Not sure how much it really matters though, so I'm curious to hear if anyone has tested this out...
Click to expand...

That is the best path to follow for rifles you require real precision from.

I've done enough experimentation with weighing brass to decide it's not for me, especially with hunting or casual shooting rifles.
 
I load for hunting and varmint shooting only, not competition. I do believe weight is directly proportional to volume & capacity , and haven't been convinced any other measurement of case capacity is necessary or very helpful for hunting loads. I weigh mixed lots of unknown cases in order to find out the difference between manufacturers / head stamps. I sort accordingly, usually keeping a batch of cases to all one manufacturer but also often finding two manufacturers / headstamps that are effectively the same. +/- 1 or 2 grains is OK by me for cases of 308 or bigger size. No need to segregate those. Sometimes, "lots" from the same manufacturer can vary quite a bit too. I sorted some very old and heavy Norma 7x57 brass I have vs new Norma brass that is 20 years newer and 10 grains lighter. That is a capacity / weight difference that is noticeable when shooting, and loads in those cases need to be adjusted.
 
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