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Old October 18, 2006, 07:39 PM   #1
Ammo Junky
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Weighing rifle brass?

I tipicaly dont weigh brass. I usualy buy new rifle brass for bolt guns and keep lot #s toghter. For ar's or hand guns I load on a progressive. I use lc brass for the ar, the few I find ( I shoot outside in a frequently unmowed area), I load untill they need trimmed. :barf: then out they go. Semi-auto hand gun gets mixed brass and most of it stays where it lands. Revolvers mostly get starline brass as it last forever and two days. On a whim I had bought some X1 fired factory test brass 3006, 308, 243. I got it so I am gona use it. Since there is know way to tell lot #, I thought I would make the most of it and at least weigh the brass for uniformity. I have found that most of my new brass (winchester) lots varry 3 to 4 gr. I have been sorting by +/- 1gr and round the tenths. This gives me an extrem spread of 3.9gr. This is very similar to what I find with the new brass so I am going with it for now. Those of you who weigh brass regulary, how narrow of a range do you shoot for? How much variation does it take before you actualy see a difference on paper or chrono? I found my rem 3006 brass weighs 10gr more than win and thought that would make a big difference, but when I am finding more than 10gr difference in my rem 243 brass alone, I wonder if 10gr will really make as big a difference in performance after all. I have found that in 25-06 85gr bullet H4350, the win brass takes 1.5gr more powder to make the same velocity.

TIA
AJ
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Old October 18, 2006, 10:05 PM   #2
Jim Watson
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The old NRA rule of thumb was that 11 grains of brass equalled one grain of powder capacity. Not far from what you see in .25-06.

I weighed some new WW .223 brass for target shooting. I keep it in one-grain lots. I got two big lots, 95 and 96 grains with small batches of 94 and 97 grain outliers. I have just a very few 93s.
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Old October 19, 2006, 03:52 PM   #3
castnblast
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I don't weigh my brass, and haven't had many issues w/ my 22-250, 7mm rem mag or 300 win mag. But I'm happy w/ my 3/8" group w/ the 22-250, So I figure why bother 7 mag is a bit wider, around 5/8-3/4, but I know it is the flinch factor.
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Old October 21, 2006, 11:41 AM   #4
temmi
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I do weigh my brass and it is one of the things I have noticed which have helped the accuracy of my loads. I understand there is a world of people who disagree… but this is my finding and opinion. Obviously we need to start with the same brass manufacture… and ideally the same lot.

First I do my standard new brass prep .
FL size
Trim to Min Length
Debur & Chamfer
Uniform Primer Pockets
Debur Flash holes
Tumble clean
Weigh
Fire form

Then I will do a little more prep
Trim to Min Length
Debur & Chamfer
Clean Primer Pockets
Uniform Necks (Thickness)
Tumble
Brush the inside of necks
Weigh & Sort

It takes a lot of brass to get 20 get which weigh +/- .5gr
But I believe it is worth it … and I enjoy it

Given you also weigh and sort your bullets and weigh each charge, this will let you weigh each completed round for a final check…

I guess I have more time to load than to shoot…
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Old October 21, 2006, 05:51 PM   #5
Ammo Junky
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The old NRA rule of thumb was that 11 grains of brass equalled one grain of powder capacity. Not far from what you see in .25-06.


Thanks Jim, that is the kind of info I am looking for.
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Old October 24, 2006, 01:47 AM   #6
amamnn
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Depending upon the degree of accuracy you are going for, you may want to check case volume rather than weight. There can be quite a surprising difference in the actual capacity of cases that weigh nearly the same and believe it or not, you can actually find heavier cases that have more volume than some lighter cases. This variance is most pronounced in new, non-premium brass and can be a problem with neck sized brass, especially if the chamber of the rifle where fireforming is done is a bit loose and brass rebound is not controlled. We're not talking huge differences, but it's something benchrest and long distance varmint shooters obsess about.

When I was first informed of this apparent paradox, I did not believe it, but I checked a dozen LC .223 rem cases that all weighed within .1 grains of each other. I filled them all up with water, using a small syringe, emptied them into a powder pan and weighed the water. Mostly, the capacities all weighed out within .1 grain of each other, but I had one that was .5 grain heavy, a pretty big variance in a small bore round. Since then, I sort my cases by weight, but I also check the volume, using clean fine grained sand. Every now and then I get a surprise and cull it, even with Lapua or Nosler brass. Full length sizing and careful control of the head to shoulder length and neck length helps a lot. Since using this method, I've cut down on mysterious flyers.

I'm told that the reason that you can get odd volumes is because of variations in case wall thickness and the relation of the head thickness to wall thickness. Cases can be made with a heavy head and thin wall as you approach the shoulder and vice versa, which affects the volume noticably when compared with a "normal" case. New or neck sized brass may not have shoulders set at exactly the same length. A case with a short shoulder and a long neck may have a smaller volume than a heavier case with a shorter neck. Again, these are small differences, but the various small variations can add up to the difference between first and third place in a match.

Most shooters will probably not need to worry about these little details, but those who want to shave 1/8 MOA or so might be interested.
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Old October 24, 2006, 08:30 AM   #7
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Great reply, and it further explains my previous question you gave a great answer to.
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