when weight sorting brass (7/08) how much weight differential between individual groups?


bounty hunter

For general big game cartridges I use .5 grains each way as a limit.

I do not sort hunting brass unless it is for Long distance (500 yards) Then .2 gr plus or minus

For 100yd groups,I keep them within a 1.0gr spread or less if possible.For longer ranges,I'd narrow it down to the least I could.That's in groups of 50 brass.

quote:

how much weight differential between individual groups?

Hey BH, It kind of depends on a couple of things:

1. How many Cases you have in the original Lot. If you only have 100 Cases to start with, it makes it difficult to get very many all alike, or real close together. So, if you are sure you are going to have a rifle chambered for that particular Cartridge, for a long time, then getting 500-1000 cases to start with helps end up with a bunch just exactly alike.

2. Number of Cases you want in a specific Lot that will comprise a Case Set . The smaller the "Set", the more Sets you can get that are just alike, or with a small spread.

3. What you intend to actually Hunt with the Case Sets. If Deer hunting, you might only have 9-18 Cases in a Set, where with Varmint Hunting, you might want 50-200 Cases in a Set.

4. Distance you will be using the rifle. With my 444Mar, I know it will only be used up close, so weight segregation is not critical. For the rifles I use at long distance, I really prefer all the Cases in a Set to be alike, but if they are off 0.1gr-0.2gr it really wouldn't matter.

5. Size of the individul Cases. In a smaller case like a 223Rem, a 3.0gr difference between cases is obviously a larger "Percentage" difference than with a Belted Magnum Case.
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I'm not real sure it would be possible to say if you have a Case Set spread of 0.Xgr - X.Xgr that you will begin to be able to tell a difference between their groups. The normal Variables between individual rifles and loads would create a wide range of answers for even one Cartridge in multiple rifles.
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One thing you can do is segregate 5-9 Cases at each end of your "Weight Spread" for a Test. Using a Load you know as accurate, load up both Sets and shoot a couple of Targets. You might see a wider group, a slight shift in the Point-of-Impact, both, or no difference. If it happens to be no difference or only a small difference, then you need to decide if it is worth all the effort of creating the Case Sets for that rifle with those specific Cases.

I will still do it, because it adds confidence to the Final Load, but I might be wasting my time.

Good hunting and clean 1-shot kills.

I use .5 gr for all rifle cases.

thanks guys---------- i'll start on that project as soon as i get back from elk hunting in colorado-----leaving in the am. the first time that i have been excited about a trip in several years.

hot core---don't agitate anyone while i'm gone---you have that ability you know--good common since advice on the weight sorting of brass--THANKS

b h

Hey BH, You are probably already gone, but best of luck on the Hunt.

Good hunting and clean 1-shot kills.

speaking of sorting cases..what brand scales you use?

Hey Paul, For years and years I just used my old 1010 Ohaus.

Then a couple of good buddies got electronic scales and let me borrow them to weight-sort cases. The electronic scales definitely speed up the process and are well worth having for that alone. Any little breeze can cause fits with them - from an open window, furnace, air conditioning or someone moving around you when you are "trying" to use them.

Still do my Loading with the old 1010 though.

Best of luck to you.

If I buy a 500 or 1000 bulk 308 or 30-06 cases, I will weigh them all on an electronic scale. With one 500 case group, I found about 30 cases that averaged maybe 15 grains or 20 grains more than the other 470 cases. What I had were two production runs of cases mixed together. I have weighed 1000 new Winchester 30-06 cases and all were within my self imposed 4 grain spread. So I used them all as is. For 1000 yard shooting with a 308 I try to keep brass within a plus or minus 2 grain spread, which is a 4 grain extreme spread. At extreme range you really want to reduce your extreme velocity spreads, so I weigh charges and try to use brass of the same internal volume. Which I assume is related to weight in brass of the same headstamp.

Now what about you pilgrim, are you shooting at 1000 yards? Maybe 600 yards?. Well out to 600 yards good ammunition is very important. Shoot stuff with the same headstamp and same number of times reloaded. But what is even more important at that range is good bullets, good barrels and good bedding. Then comes primers (primers are something we have no control over but make a difference) and powder. This is assuming you have the shooting skill to hit a three foot target bull at the range. This is not a given. That is why the target frame is six foot by six foot.

One of the absolute best shooters I know, a Wimbleton cup winner, he uses good brass, good bullets, tests his loads, and tests his primers. And that is about it. No worrying about primer pocket trimming, no .2 grain case weighing, absolutely no bullet runnout. That is benchrest stuff and makes a difference in that game. It is below the noise level in a handheld weapon.

Lets say you are planning to shoot out to three hundred yards. Just use good bullets, good components, good load, and fire away. If you can see on target any difference in case weight, bullet runnout, any of that benchrest stuff, than you are a better shot than any National Champion I have been squadded with. I have not been squadded with them all, so maybe one of them out there can tell me that it makes a difference. I have shot excellent scores at three hundred yards with some pretty callous loads. The bullets were the same, the powder was the same, the primers were the same. And that was about all that was the same.

This benchrest stuff is good for selling reloading equipment. Shill gunwriters have to push this stuff, so they write long articles extolling the virtues of expensive pieces of equipment. They sell, you buy, the industry is happy and no one tells you its all a placebo effect. People just don’t shoot enough to find out that they are the biggest source of inaccuracy. So they buy the equipment. Buying expensive reloading equipment won’t compensate for lack of shooting skills. And that is only gained by shooting.

I have weighed a whole bunch of brass both wet and dry in various calibers to see if I could get a better feeling of water wt vs case capacity.

Did it with my same-fired brass in a couple different calibers I own.....

This is with more than 50-shells of a lot. No mixing brands or mil-year headstamps.

Short answer, I could not correlate case capacity with dry weight -- even within same lot, same brand brass, prepped brass.

Based on this, I sort fired cases by water capacity and pretty much ignore dry case weight by itself.

Best regards

John

TruckJohn; What you have posted is depressing to read. Dry weight is easy to measure, wet weight has got to be messy. If there is no correlation between weight and case volume, then what I have been doing is the placebo effect.

quote:

Originally posted by SlamFire:
TruckJohn; What you have posted is depressing to read. Dry weight is easy to measure, wet weight has got to be messy. If there is no correlation between weight and case volume, then what I have been doing is the placebo effect.

It is a messy pain in the rear.

I honestly thought there would be a good correlation. Logically, it makes reasonable sense that lighter cases of the same length would hold more water..... The data I have collected just doesn't confirm it.

Being the sort that just can't leave well enough alone, I decided to check -- Just to see.

I've measured cases that had identical case volume when tested with water, but radically differing weight - then I looked at the extractor cut and the one case (same brand) was markedly different to the other.

Could be that's where a lot of the weight difference could lie, and it would or should not affect the internal volume (hence ballistic performance) one jot.

quote:

Originally posted by TruckJohn:
...I could not correlate case capacity with dry weight -- even within same lot, same brand brass, prepped brass.

Based on this, I sort fired cases by water capacity and pretty much ignore dry case weight by itself...

Hey John, Once you went through that exercise, did you happen to try "Test Firing" any of those Water Capacity Sorted Case-Sets in comparison to the Weight Sorted Case-Sets?

The reason I ask is because after I "Weight Sort", I can take a Light Case-Set and a Heavy Case-Set and see Point-of-Impact movement or Group Size changes.

And I can take similar weight Case-Sets and see the Groups are of a similar size and location on-Target.
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Not arguing with you, if you prefer Water Capacity Sorting, and if it produces great Groups for you, then I'm all for you doing it.

I had a similar conversation with a knowledgeable reloader that used to hang around H.A. a good many years ago. He had done a whole bunch of Water Capacity Sorting and it was wearing him out.

One thing he mentioned to me was "Marking a Case that had a Flier". Then if the same Case had another Flier on the next reload, that Case was removed from the Case-Set.

So, one way or the other, if a Case-Set ended up with a Case that had "something different" about it, the Case was identified and removed from that Set.

A lot of the things I do with my Case-Sets may be TOTALLY un-necessary, but I will continue to do them since it is my time to use as I see fit. And as we all know, the proof of all the effort we put into Case Prep can be seen or not seen on the Target.

Best of luck with the Water Sorting.

One thing about water weighing is the fact that every piece of brass may have minor size differences which fluxuates the capacities. Just because the brass was fired in the same chamber doesn't mean it was exactly the same size when extracted therefore internal capacities are different from one piece to the next even if the brass dry weighs the same.

Any of you have the same theory on wet weight?

I've always thought that if you dry weighed the same lot after you prepped to sort that you'd be about as close as one could be as far as precision goes.

Reloader

quote:

Originally posted by Reloader:
One thing about water weighing is the fact that every piece of brass may have minor size differences which fluxuates the capacities. Just because the brass was fired in the same chamber doesn't mean it was exactly the same size when extracted therefore internal capacities are different from one piece to the next even if the brass dry weighs the same.

Any of you have the same theory on wet weight?

Reloader,

Yes Reloader, this is exactly what I was trying to explain to TruckJohn in another post.

Take some cases and put them in a reloading tray/block with the mouth up. It doesn't matter if it is taken from the chamber or the FLR die. Take your mic and measure at the level of the tray. This way you can measure each case at the same point. Rotate the case as you measure and take the smallest or largest measurement and compare it too the other cases in the same way. You will quickly see there are differences in case diameter. Prep as much as you want and then measure again. The variability is still there.

IMO case capacity is dependant on how the brass in the mid section of the case expands and then contracts when fired or resized.

Jim

I have weight sorted .257 Roberts +P win brass and measured groups and then shot random weights and measured groups, and if there is any difference it cannot be measured when the best group is .4 moa.

Maybe someone who shoots .1 moa all the time could tell the difference.


This guy went to Camp Perry forever:
http://groups.google.com/group/rec.guns/browse_thread/t...=en#12d8eb8e58ed7637

quote:

From: Bart Bobbitt - view profile
Date: Tues, Jul 19 1994 8:01 am
Email: b...@hpfcla.fc.hp.com (Bart Bobbitt)
Groups: rec.guns


Case weight spread is near the bottom of the list of Things That Make
Accurate Ammo. A 5-grain spread in .308 Win. cases will permit groups
of 0.5 MOA at 600 yards and 1 MOA at 1000 yards, providing the rifle
is built properly with the right parts. And even brand new, never
fired cases can do and have done this.

Getting a uniform lot of primers is probably the most important thing
for accuracy with the .308 Win., especially for ranges of 300 yards or
greater. And using milder primers is probably a very close second place
issue. Then using a compatible powder (4064 for 160gr.+ bullets, 4895 for
lighter ones) completes the issue. As long as velocity spread is less
than 25 fps, that'll do fine.

More important than case weight spread is case wall thickness uniformity.
But both Winchester and Federal cases are pretty good in this regard.
Military cases are pretty bad in this department.

So, you can sort cases by weight if you want to. But I think you'll be
hard pressed to detect changes in accuracy caused by case weight spread
alone. Too many other things exist that'll cause bigger differences.
You'll probably get 1/20th MOA improvement in groups at less than 600
yards, 1/10th MOA improvement at 1000 yards.

BB