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Weighing brass?

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bandur60

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Feb 17, 2008
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Big Sky Country (not in lala land)
Had an interesting thought today while prepping brass for fireforming in a 22-250 Imp. After tumbling, sizing, and trimming 60+ pieces I decided to weigh some (ended up doing all of them). Most, maybe 80-85% came in at 156-160 grains, but a few from 148 up to 162. So got to wondering what effect that would have on case volume and pressure. In the end I reasoned that brass is many times more dense than powder (SR4759 in this case, and Winchester brass) that it probably doesn't have much effect unless maybe between the lightest and the heaviest cases.

What thinks the brain trust here?
 
For 308 win brass I'm happy if the weight variation is with in +or- 2.5gr.
Neck tension is a major concern, if that isn't right you are pissing in the wind.
 
Your figures show about a 9% max spread in weight. For my reloading this is pretty inconsequential. If you are chasing shaving 1/10th moa's you should divide it into batches of like weights and keep each reloaded batch separate. Myself, I wouldn't bother.

What function is the ammunition going to be used for?
 
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It all depends where the extra weight is or is not. The only way to know is to do a case capacity check. I've done volume checks on sorted weighted cases and it's pretty meaningless. I've had some that were heavy that had more volume than the lightest ones. And light ones with less volume. It's all about were the weight is distributed.
 
Mixed head stamped or mixed lot numbers of brass can vary wildly when weighed, I prefer to cull out the unexplained by running a well built load past a chronograph.
It’s easy to see how just removing the odd balls can produce results see on paper.
 

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I sort by weight but the lupula brass for 6.5manbun which has a variance of less than 1 gram over the 500 cases I have for my rifle. If I remember correctly the lightest cases are 10.3 grams and the heaviest is about 10.8 grams.
Cheaper brass has a variance of more like 2 grams just in a box of 20.
 
I 1.sort by headstamp, and 2. make batches by weight. I'm in the position where I'm picking up hundreds of cases a trip, and making 50 or 100 round lots. My primary RP 308 100 round batch has a total .6 grain spread. It cost me nothing but time to do that. If I was buying brass there is zero chance I'd use this process.
 
Some people I know swear that weight sorting is really important. I've never weighed my brass and I haven't run into any major problems.
 
243winxb said:
Produce the fliers.
Full BR prep, with neck turning. Sort to 3/10 grs.

If your rifle can tell the difference?
Click to expand...

sfl_gunner said:
Some people I know swear that weight sorting is really important. I've never weighed my brass and I haven't run into any major problems.
Click to expand...

Something I learned many years ago: if you think it makes a difference, it does.

Everybody has their own particular bugaboos. Some focus on one thing, and some on another. It's all good.

Me? I weight sort for target ammo.
 
It's thought that heavier cases may have smaller internal volume. Although I've done it, never had a need/desire to weigh sort my rifle brass. I'm not a real good rifle target shooter so the added consistence of like weight brass isn't real important. My best consistent performing handloads were 308 Winchester w/LC brass, Norma HPBB, 168 gr "match" bullets over IMR 4865. Gave me 7/8" groups @ 100 from my Ruger 308 bolt rifle...
 
Unless you are a bench rest shooter and competitor you have entered a black hole. Good way to kill a lot of time but if you are like me , no t a competitor it is not necessary for my groups are small enough for hunting, not competing. I do weigh 22lr bullets as grouping will be more consistent but than again I still get occasional flyers.
 
If you want to shoot little bitty groups it matters, if you have a gun that is capable, I will start out with new Lapua brass say 300 out of same lot and pick out a 100 or so that are the closest
 
Paper plate accuracy at 100 yards doesnt count as small groups.
Every SAMMI cartridge I know of lists brass volume, it’s kind of an important factor and consistent bullet hold( neck tension) creates consistent pressure so if volume changes and pressure changes then bullets impact a different point on the target.
Guys just dont shoot far enough to see it but that doesn’t mean it’s not a real thing.
 
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bandur60 said:
OP here, appreciate all the replies.

I'm through with worries about this, I'm just shooting 100-200 yards on paper for myself, nothing serious going on. I do sort by headstamp, and saw that Win is overall heavier, but only by a couple of grains. Retired, so the time was cheap....
Click to expand...

That was actually the intent of the machine I posted above as they do tend to be closer in weight by brand of mfg. Never really finished it because I began looking into optical/machine learning for the job.

Anyhow, conversations about the utmost accuracy shouldn’t ever have mixed brass even mentioned. Even if you do sort by headstamp they could have been produced years apart from one another, hurting the consistency one is striving for.

My most accurate groups were fired with a hand full of cases, made to fit the firearm and never fired in anything else. I do have tons of “range” brass but they don’t have the same intended use.
 
South Prairie Jim said:
Paper plate accuracy at 100 yards doesnt count as small groups.
Every SAMMI cartridge I know of lists brass volume, it’s kind of an important factor and consistent bullet hold( neck tension) creates consistent pressure so if volume changes and pressure changes then bullets impact a different point on the target.
Guys just dont shoot far enough to see it but that doesn’t mean it’s not a real thing.
Click to expand...
Where are you seeing brass volume tabulated in the SAAMI spec. I am not finding it.
 
B9782CCB-1BA8-4361-9D7C-B06130A6B9F3.png
For argument sake let’s say Winchester brass is being referred to here shows 56. gr of h2o yet Nosler brass lists 52.0 gr

That’s a significant difference in pressure.
 
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