Number of reloads effect impact

Discussion in 'Reloading' started by arrow, Mar 18, 2012.

  1. arrow

    arrow Well-Known Member

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    I was wondering if the number of times brass has been reloaded effects impacts in any way. I keep them all sorted for number of firings. I trim when they get past max length. But will velocity and impacts be the same between a twice fired brass and a 4 times fired brass before retrimming? I know the simple answer is to try it, but I haven't had the time to experiment with this. Also will these 4 fired brass impact the same as the 5th after I have trimmed? thanks
     
  2. kc0pph

    kc0pph Well-Known Member

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    I believe the Most correct way to say this is every time you fire your brass the case capacity gets slightly more. Brass is moved around and we even trim for OAL. Well that brass will change POI because case cap has changed (Everything is to outside dimensions so less material same outside dimensions means more case cap).

    The Flash Holes get slightly larger with each firing and the web gets pushed back as well, primer pockets get loose.

    Precision shooting is not about your load and rifle combination (although a big part) it is about consistency. You can not be consistent with the above mentioned faults.

    The Wrench in the works: Take Your brass that you have CAREFULLY ensured is Identicle. You have 100,000 pieces and you need 10. Check them for everything to ensure they are perfect. Take them to a lab where they have expensive tools that I dont even know about. Ask them if all 10 are identicle. I bet even OAL will be different because they might measure in pico Meters when you measure in ten thousandthsn of an inch.

    The Point is there is a lot that is out of our hands, but the simple things that we can control easily lets control. You are doing a good thing by sorting brass by times fired. Will it change your POI? I bet You Cant shoot well enough to tell. (No disrespect but not sure anyone could tell 2x for 3x.)

    Bench rest shooters shoot 1/10th moa and i do not believe your could really tell on their targets either. But then again I will get someone who says your POI will change 4.723 MOA per firing.

    To Sum Up.
    Do what You can do and what is easy to make sure Round 1 is identical to round 2. The longer your shots the more you care.
     

  3. arrow

    arrow Well-Known Member

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    I guess what I am asking is lets say I have a good load. .308 win 44g varget 175 smk. I have a good seating depth and this load works for me. Lets say I have batches of brass in 20's. They all start off as close to the same as I can get them. I start building data on long range targets and recording them in my book. Lets say I go to shoot the same 650 yard target at the same elevation at the same temperature but now that same brass has been reloaded 3 more times. Will the impacts be the same as the first loading, (by first I mean first after fire forming the brass.)
     
  4. CliffM

    CliffM Well-Known Member

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    I have gone to annealing competition brass every firing mostly because I am not organized enough to keep brass sorted as to the number of firings.
    As the hardness of the brass changes each firing so does the neck tension so does the POI.
    I recently bought what has been the worst batch of winchester brass I have ever used. The hardness of the brass varied alot from case to case. Loads would shoot good at 100yds but the es. was sometimes 100fps. After annealing the es. came down into the single digits. Groups will stay under .5moa past 1000yds now.
    I wouldn't say that all brass in all rifles will have the same sensitivity to neck tension but mine sure show it.
    Cliff
     
  5. kc0pph

    kc0pph Well-Known Member

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    Annealing Your brass (in this case) is like putting mud in potholes. You have to do it often or the holes continue to get big, but it does smooth out the road. I do it every 3 firings. But Ill repeat what i said before only a benchrest master (and maybe) would be able to tell the difference between 2x brass and 3x brass. Do your best to stay organized but life happens.
     
  6. Greyfox

    Greyfox Well-Known Member

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    I have done a lot of work in this area with my 308. I have found that I can get 8-10 reloads using Lapua with good ES without doing anything except trimming after 4 or 5 reloads. I found that the neck tension of the dye effects this. I seems the greater the tension, the more variability as the brass is worked. I size down .001-002" max and do not use an expander. I can feel a difference in neck tension if it occurs and put that brass aside. Lapua is the most consistent I have tried and I now use it exclusively. I have found Winchester brass to to be thinner by a couple of thousandths and much harder to control neck tension with repeated reloading. Annealing helps a lot as you have found.
     
  7. Mikecr

    Mikecr Well-Known Member

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    The question lacks a critical qualifier: Your sizing
    To reload your brass, you sized it.
    How much?
    What are you changing?
     
  8. arrow

    arrow Well-Known Member

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    I am using a rcbc full length sizer die. I have it was the expander ball and the die is set to just bump the shoulder. I don't have my notes with me now but it is pushed back .002" I believe. So I am only bumping the shoulder a little bit back each time. Could someone explain their whole process of keeping brass sorted and ready. Such as after 3 anneal, after 4 trim, after 8 throw away. And whatever else that is being done. I just don't want to work up data on a gun with 2 and 3 times fired brass than once the brass is on its 6th firing and after retrimming they are impacting differently at a distance. i start off case prep by trimming all to the same length, truing and deburring primer pockets, than I fireform before I start working up and using the brass.
     
  9. Mikecr

    Mikecr Well-Known Member

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    If you're trimming so much, you're FL sizing.
    So your brass is never reaching a point of stable capacity anyway.
    As mentioned, with each trimming, your capacity is changing a little bit.

    Nobody can predict when this would take you out of tune to a point of detriment. If nothing else, because we all hold different standards of performance, and we all size a little differently(our chambers & loads & dies are different).
    It's good to get an impression from other's experiences, but keep in mind that in reloading, we are each on our own really.

    I keep my brass together in lots of 30rnds. They are never separated from each other. I don't reload any of them until I reload all of them together, by lot.
    When I replace one, I will replace them all.
    But in my case, this will probably never happen(hasn't yet), as I don't FL size & don't have to trim. I also shoot at a relatively low rate(cold barrel), and avoid hot loads.
    Any departure from a plan like this leads to an abstract IMO, which is what I suggest as unpredictable.
    But if you plan to replace brass at a set rate, well that takes it back to predictable.
     
  10. kc0pph

    kc0pph Well-Known Member

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    After new brass is sorted (Weight, case cap...) and trimmed, primer pockets cleaned and such all of the work you would do to new brass I take an engraver and put dots on my brass. Right on the headstamp. This way I know what lot is what lot. Dont have to worry much. Once i start loading a lot i shoot every piece of brass before i start loading that same lot.
     
  11. Bart B

    Bart B Well-Known Member

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    Friend of mine took one Federal brass .308 Win. case to the range with his match rifle and reloading tools. Clamped the rifle in his machine rest then loaded his first round then shot it, full length sized and primed it, stuffed 42 grains of IMR4895 under a Sierra 168 HPMK and fired it 56 more times. Had to trim the case back about 10 thousandths every 10 or so shots. Chronograph showed a 26 fps spread in muzzle velocity across all 57 shots from that same case. 57 bullets all went under 1/3 MOA at the 100 yard target.
     
  12. kc0pph

    kc0pph Well-Known Member

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    Well I guess that shows that it does not matter how many times it was fired. And 57 times that is insane! bet the primers were falling out.

    One question How did he clean the lube off of them in a timely manner? I have to wash mine and let them dry. Even if i use an oven it takes hours.
     
  13. Bart B

    Bart B Well-Known Member

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    No primers fell out. The load was maximum but not overly so.

    Rag lightly soaked with laquer thinner of naptha; I now forget. When I shot a Federal .308 Win case making the same "shots per case" test using the same load, I used a rag with naptha to clean the lube off the case after it was full length sized. I ran out of test powder after 46 shots. And no primers fell out of my case, either.
     
  14. kc0pph

    kc0pph Well-Known Member

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    And you hear people preaching that 308 brass only lasts 6-12 firings IF YOU TAKE CARE OF IT! I always wondered about cases lasting forever. It took 22 rounds before my 270 had a case-head rupture (Not quite Separation). Fathers AR-15, loads about 50 rounds of brass ONLY and has shot it for over a year VERY actively. I would be suprised if he has not loaded them 100 times a piece. (There is at least 50 boxes of 69gn SMK empty in the gun room).