velocity based case sorting

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by milanuk, Sep 19, 2004.

  1. milanuk

    milanuk Well-Known Member

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    Well, I've got a new itch to scratch, so to speak.

    I recently had a long conversation w/ a gentleman that is a serious F-Class and 1K BR shooter. The topic of sorting cases came up, water volume vs. weight sorting, weight sorting into 1-2% big batch vs. making up 0.5gr lots, etc. He had a different approach that on the surface seems to makes sense (sure seems to be working for him!), and I though I'd run it by y'all and see what you think about it.

    He gets a (very) large quantity of cases up front, (Lapua .30-06, in this case, as his round is a 6.5-06), and completely preps them, i.e. primer-pocket uniforming, flash hole deburring, trim, chamfer, deburr, neck turn, the whole enchilada. Then he loads them up w/ a known good load that shoots fairly consistently, stable velocity. *All* of them. Fires the rounds one at a time, one every three minutes to keep the barrel temp stable, chronographs every one, and writes the speed on the case itself w/ a sharpie. Loads them up again, and does this again.

    At this point, he has all of his cases fired twice, as fully fire-formed as they are going to get (btw, he uses a separate barrel chambered up w/ the same reamer so one barrel is for fire-forming and load workup, the other is his primary 'match' barrel), w/ velocities written down on them. He then sorts them by what his target velocity, E.S., and S.D. are. I.e., if he wants an average velocity of 2950fps, w/ an extreme spread of 10fps, he'd gather all the rounds that went that speed into one 'lot', and keep them together for the rest of their natural life (15 loadings total). He feels this is the most realistic way to sort cases, as you are not dealing w/ variables of case head dimensions affecting weight/volume, surface tension/bubble affecting water volume, etc. Just measuring what the actual real world speed is out of these cases.

    Sounds good. Expensive and time consuming, but if you are really after the lowest E.S. and S.D., it might be worth it. Not sure how the variance within even an individual powder or primer lot, or the finite accuracy of the powder scale or chronograph would play into this. As I said, the guy is shooting pretty competitively, and firmly believes having effectively zero E.S. is a big contributor.

    Comments, thoughts, suggestions?

    Thanks,

    Monte
     
  2. chessman

    chessman Well-Known Member

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    Interesting. I've never heard of this, but it makes sense. Rather than trying to measure all the little things that create variation, just measure the variation itself and don't try to figure it out - just live with it. I think I like it (at least, it's worth a try).
     
  3. BountyHunter

    BountyHunter Writers Guild

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    John Hoover in PA does that for the 6.5-284s his family uses. Based on results it sure works. They shoot light guns in the heavy gun class and kick but normally.

    By the way he only uses "old white box" WW 284 brass and has a couple unique steps in his reloading process.

    I use a Juenke machine to do something similar. After fireformed, the cases are spun on a Juenke and sorted by deviation units and that seems to work also.

    BH
     
  4. TOM H

    TOM H Well-Known Member

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    Milanuk, I think your friend has the right approch. I don't load for the long range game but have heard the es if more than 10 can account for different size groups at 1000yds. I think some case prep is ok but you still have to fire that round and be able to slect those match case and alot of different methods to doing that.
     
  5. Mysticplayer

    Mysticplayer Writers Guild

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    Monte, I do something very similar and it has really helped me with consistent groups. Instead of just measuring vel, I shoot for group size.

    The min. distance I shoot at is 180yds (just the way my range is). 250yds is better. Assuming conditions are calm, I shoot groups with the best shooting load. I look for any shot 'out of the group'. I mark the brass. Odds are, that brass fired again will throw the shot out. I pitch that brass.

    What I have left over is brass that is consistent UNDER FIRE. They may vary when you measure different aspects but that doesn't bother me.

    I have tried the weight and volume method. Both can give bad results for various reasons. The only way to know about the brass is to shoot it. By doing this, I have been able to get match quality from gunshow mystery stuff to mixed lot onced fired.

    I find that annealing the necks can help increase consistency when dealing with mixed lot mystery stuff.

    It is expensive and adds wear to the rifle but I need the practise anyways. It will give you the best brass I know how to 'make'.

    Jerry
     
  6. milanuk

    milanuk Well-Known Member

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    Jerry,

    I told the fellow I'd heard a similar method, basicaly keeping the shells that shot an 'X' (from an old score BR shooter) in one coveted pile. His response was that he felt the chrono method eliminated any human error factors. Still, it's interesting to see that others employ similar methods.

    The big thing that was daunting about his version (other than the extra barrel) was the *2000* pieces of Lapua brass he starts with. That's over $850 in brass _alone_!!! Yikes. But, as was mentioned, if winning is the goal... it apparently seems to help.

    I was kind of hoping to employ a variation w/ a couple of upcoming .308 Winchester projects. 500 pieces of brass dedicated to each gun, and velocity sort them into 'batches'. I didn't figure 500rds of test firing was too much of a chunk out of the respective lives of a .308, and probably would provide some much needed trigger time. Afterwards I hoped to sort the brass into say, 50rd batches, and keep them separated in the blue Dillon shell boxes. For the one rifle (long range prone - any-any/F-class/Palma), most all the shooting is for 'score' so keeping the shots consistent in velocity/elevation in one box would work just fine. Minor changes from one box to the next would be relatively easy to account for. For the other gun, which is more for hunting and/or tactical matches, going from one box to the next could be an issue. I don't really hunt LR all that much w/ a .308, so that part wouldn't be too big a deal, but for the matches having to know where the cold bore shot was going to go could be interesting, depending on which 'box' I'm using.

    Ah, well, it'll give me something else to worry about [​IMG]

    Thanks,

    Monte
     
  7. Mikecr

    Mikecr Well-Known Member

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    Somebody try it.
    Take one formed case/load, measure it's resultant velocity over a chrono.
    Then reload same and measure again.
    Maybe try it a third time.
    Does it work?
    Let us know.
     
  8. TOM H

    TOM H Well-Known Member

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    I load at the range and have done that with a 300wsm factory rifle got a veocity spread of 16fps on 3 rds that was with H-4350 got alot more using R-19 and R-22. On my 6.5x284 using once fired cases Win 284,Hornady 6.5x284 and laupa 6.5x284 the spread was about 24fps once got velocity down to the 2900fps range. The spread I'm using is between high and low velocity. Since I'm not into the long range game ES and SD doesn't help for my type of shooting. I fired form some 7x57AI case using RWS brass and those were the most unifrom as to velocity less than 5fps on 5 rds. About 20 yrs ago had a tight neck 6x284 built with a 1/14 twist 30" barrel want to shoot some berger 68gr match bullets over 4000fps got over 4200fps had a velocity spread about 40/50fps backed the load down till groups started to open up and settled on that load so checked velocity was alittle over 3850fps and spread was cut in half had the same thing happen with my custom 300wsm with that 5r barrel was pretty close to 3300fps with a 165 gr bullet got down to alittle over 3100fps. I've got a tight neck 6br and a 6br shortentalldog gets better velocity less velocity spread and better groups with the shorten 6br than the standard 6br. I've got a tight neck 308 that I'm going to start shooting one of these days its set up for the 168gr match bullets all I've managed to get done is some brass turned. When I started to shoot BR I would start out with about 60 cases and get maybe 30 for match and use those till got a new barrel and if was lucky might use those cases on the next barrel. I've still got a 100 of the old Sako 220 Russian case and afew that Skip Otto put in the new bushing for the primer pockets. Well good luck.
     
  9. milanuk

    milanuk Well-Known Member

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    You first, man. [​IMG]

    That's why I posted here, to see if anyone else had been fooling with it.

    Actually, once I get done w/ the other 300 or so of my ~500 cases of 6.5-08 (3rd firing, now it's time for trim, chamfer, debur, uniform the primer pocket, general inspection, etc.) I'll be ready to get back into experimenting. But it's slow going w/o a Gracey or Giraud to do the grunt work; I've got a Wilson trimmer and all the other stuff I chuck in a drill press. Still takes time, though.

    Monte
     
  10. Mysticplayer

    Mysticplayer Writers Guild

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    Monte, do all testing with fireformed case. Fresh out of the bag, there is too much variations to matter.

    so I fireform, then load for accuracy testing, then confirm either through accuracy testing or on LR targets/gongs. At least I get some 'shooting' while I am sorting brass.

    I find that if a lot of brass shoots well, I don't need to sort every single piece. But, I don't shoot 200m BR where a tenth is too much.

    Anyways, have fun with your testing. The bullet, powder, and brass companies thank you for their new retirement cabin.

    Jerry