Weight sorting brass

Discussion in 'Reloading' started by nddodd, Jul 7, 2012.

  1. nddodd

    nddodd Well-Known Member

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    Did a few searches on this and found alot of info on smaller caliber sorting but none for ultra mag size cases. Back to my question is a lot of 3 gr + or - a good start or should they be closer than that. I'll be useing it primarily for hunting and shooting targets. The farthest would be 800-1000 yds.

    In yalls experience with the ultra mag size cases is sorting a waste of time or not.

    Thanks,
    Nathan
     
  2. Bart B

    Bart B Well-Known Member

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    Sorting cases to a 1% spread in weight's good enough for targets past 600 yards. For shorter ranges, a 2% spread's fine. There's a greater spread in muzzle velocity caused by the spread in pressure peak and curve for exact powder charge weights and what a given lot of primers will have.
     

  3. tomt

    tomt Well-Known Member

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    I was bored, so I decided to weigh my .300 WSM Winchester Supreme Nickle Brass. This brass was necked sized, trimed and deburred. Found five that weighed about 4 gains lighter than the norm. I set these off to the side. Took the rest and randomly picked out six, placed a spent primer in and weighed the brass. Then I filled the cases up with distilled water and weighed again. Subtracted the difference to see what the volume of the case are. They averaged 81.4 gains of H2O. Decided to to the same to the five lite cases. End result was about the same, not enough to be concerned about.

    Volume of case is more important than weight of case.
     
  4. Bart B

    Bart B Well-Known Member

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    Except that the more out of round a case is, the less water it will hold. Which would mean to some there's less volume in it. But that case brass still takes up the same amount of space in the chamber.
     
  5. nddodd

    nddodd Well-Known Member

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  6. FUBAR

    FUBAR Well-Known Member

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    Magnum brass sorting? Of course... On some of my big mags the brass has been as much as 8 gr +/-

    That much +/- can't be good.....It's in the head or the volume, don't really care which, just separate and segregate as I load.
     
  7. rscott5028

    rscott5028 Well-Known Member

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    Because you can go down to Walmart and buy a box of Rem Corelokt and kill a B&C trophy, some might say handloading is a waste of time. Only you can decide whether or not something is worthwhile.

    Weight sorting is easy. So, go for it if for no other reason than to have a record of the properties of the brass you're shooting.

    However, case volume is most likely a better predictor of consistent performance albeit more difficult and time consuming to measure.

    As for magnums vs small cartridges, it should be easier and more beneficial to measure large magnum cases.

    If you want to know if it's worthwhile, then try something scientific like...

    Record the water weight capacity for each (fired) case and sort them. Calculate the mean and standard deviation. Then, eliminate anything that's more than 2 standard deviations above or below the mean. Keep them sorted, load, and shoot them with a known good load and record your MV and group sizes.

    Graph your MV along side the case capacity and see if they track in the same direction. Look at your groups and see if they're better than you normally get with this load. (probably won't make much diference for short range and a good long range load will be more tolerant of subtle MV variation than a poor long range load)

    You can get a lot deeper with proving/disproving this statistically. But, chances are that if you can't discern sufficient benefit like this, then it's probably not worth "your" while.

    -- richard
     
  8. Mikecr

    Mikecr Well-Known Member

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    I'm in the 'sorting out cases by dry weight is a bad move' camp.
    There is no direct relationship between dry case weight and capacity.
    You probably don't want to discard brass that matches the bulk in capacity just because it's dry weight is different, or to keep brass that departs in capacity even though it's weight is consistent with the bulk. Right?
    You want your brass to match in capacity, right?
    Then, measure that.

    I sort fully fireformed/unsized cases by H20 capacity, and yes you can see a difference across a good chronograph and on target from this. The difference is predicted very well with Quickload also. The affect is exactly the same as any variation in load density.
    I currently do this for 6br, 6xc, and 6.5wssm.

    While Larger magnum cases present more volume to vary(regardless of case weight), they have a much wider pressure peak(the part affected by initial containment).
    Small underbore cartridges(like a 6ppc, or 30br) can work around capacity variances through sheer extreme pressure loads.
    Both of which put affects to peak pressure, and barrel timing -from capacity variance, in smaller percentage.
    But mid-size cartridges(like mine) can't work around capacity variances, and I believe they are affected most by it.
    That's why I check it.

    You may be in a good position to check it nddodd, and you don't have to go through a lot of trouble to see if it's a worthy endeavor.
    At the range with your normal load, point a chambered round straight up & carefully lower it to rest. But don't take so long as to allow the round to heat up in the chamber more than others.
    If it's fired POI step changes away from the pack, then your load will be affected by capacity variances.
    If not, I wouldn't bother sorting it at all.

    I don't shoot any large magnums so I can't predict your result.
    My 223s don't change with this test, so I don't sort them by capacity.
    The others do -big time.
     
  9. Bart B

    Bart B Well-Known Member

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    Except that if you feel the capacity of the case is only meaningful when the outside of the case is pressed hard against the chamber at peak pressure. That's when the outside dimensions of all the fired cases are exactly the same. Then the volume of the case equals the volume of the chamber minus the volume of the cartridge brass.

    So, I weight cases to a 1% weight spread. This method may well cause the first part of the pressure curve to vary its shape more than weighing the water a case holds. It may also cause a small difference in muzzle velocity. I don't measure either one as I've no interest in either one. I don't know if anybody's accurately measured bullet drop differences at long range caused by both weighed cases and weighed water in cases that gets the same results within 1/2 inch for each test round fired. My cases sorted by weight do well enough to shoot long range groups equal to what benchrest record-holding ammo does.
     
  10. nddodd

    nddodd Well-Known Member

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    Thanks for everyone's input on this subject it is greatly appreciated. Mikecr I'll give your advice a try, thanks again guys.



    Nathan
     
  11. rscott5028

    rscott5028 Well-Known Member

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    I was hoping someone else would ask so I wouldn't look stupid.
    But, what are you measuring/testing here?
    How does this relate to the significance of case capacity variability?
    Would the results be different using a load with 90% fill vs compressed?

    thanks!
    Richard
     
  12. Mikecr

    Mikecr Well-Known Member

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    It shows that things significant to the outcome are happening BEFORE brass is mashed to chamber walls. You could dent your brass in and fire it to see similar. Same brass weight, same chamber.
    You can change velocity with dies, and unsized new brass velocity will usually be higher than fireformed brass(sized or not), even though brass weight hasn't changed.
    These things are causing INITIAL confinement & load density changes, and they do affect MV and barrel timing for many, even though the same brass will eventually expand to the same chamber.
    That weighed FL sized brass shoots well enough, does not mean specific things can be generalized, just to make it so. There are too many contributors to do this.

    The test I proposed affects only relative load density, and would not cause change with a compressed load. --I should have qualified that--
    I believe it indicates whether a combination would be significantly influenced by load density variances, or not.
    As implied, many combinations could be immune to this, while others are sensitive to it. I've tested what I shoot, and not a full gamut of combinations by any means.

    As far as same brass weight mashing to same chamber volume, I don't believe that is happening. Magnum cases especially provide for weight variance -that does not contribute to capacity, regardless of chamber(like the belt and large rim & extraction groove).
    But I think(a theory) that it may not even matter with magnums, considering their broad pressure curve.

    Mid-size cases, even running faster powder, still take a bit of time to fully fit a chamber with any clearances. Any amount of time variance, confinement variance, influences powder burn rate and the pressure peak. These cartridges still do not burn all the powder in a barrel anyway, so pressure peak timing is very significant to outcome as less likely normalized further down the bores.

    Underbore cartridges really shine with very high pressures. Not so much otherwise.
    This works great, they completely burn up very fast powders even faster due to pressure. A glitch in their pressure curve due to initial confinement, or pretty much anything else, is insignificant as they're running flat against a wall of diminished returns anyway.
    The great work-around.
    This approach is viable with powder availability & capacity that provides for it, -with enough barrel steel around the chambers.
    So far max capacity for this seems to be with the 6.5x47L, but time will really tell.
    Larger diameter tennons will be needed to go further up with this to to 28 or 30cal.
     
  13. rscott5028

    rscott5028 Well-Known Member

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    Mike - Thanks.

    Plenty to think about.

    Is Quickload much help as a learning tool in terms of modelling some of these effects?

    The demo is pretty lame and the fact that you have to wait for someone to mail a CD gives me the impression (right or wrong) that it's not nearly as high tech as they'd have you believe.

    -- richard
     
  14. Mikecr

    Mikecr Well-Known Member

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    QL is incredible. You play with it, calibrate for your/other loads, and run all sorts of 'what-ifs'.
    I was an early adopter with my first version(maybe a beta) on floppy.
    NECO is mom & pop-ish, but very reliable. I just upgraded again, and so far it's been worth it to do so now & then.
    I use QuickLoad, QuickDesign, and QuickTarget which are integrated and export to each other.

    Keep in mind there is NOTHING else that competes with QL. It is completely unique.
    And you won't regret sending off for it.