Velocity Spread- Help!

Discussion in 'Ammunition & Reloading' started by Flatfish, Jun 8, 2019.

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  1. Flatfish

    Flatfish
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    Have a 223 that shoots 1/4 minute with:
    73 grain Hornady ELDM
    Nosle once fired case (Neck sized)
    25.1 grains Varget
    Fed 205M
    Velocity is average 2948fps
    Each charge was weighed (Check weights used to verify scale)
    Bullets, primers & powder from same lot numbers

    The primers are 20+ years old (Bought/hoarded em during Great Primer Scare back in the 90s). Always stored in garage.

    For short to medium range (Under 500 yards), everything is spiffy.

    Problem is, velocity spread is almost 100fps over a 9 shot string.
    2898
    2922
    2941
    2956
    2996
    2946
    2952
    2986
    2937

    For long range (In this instance, 500-1000 yards for the sake of conversation), this is gonna cause misses.
    First plan is, try fresh batch of Fed 205M primers.
    If that don't work, I will swap out primers for another brand

    Brass (Nosler prepped cases. Fantastic quality stuff so far. Straight and round as any Lapua I have seen) is fired once in this rifle. Then neck sized.

    Never figured I would look for improvement on a 1/4 moa load/rifle. But here I am!

    Suggestions or thoughts?
     
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  2. Greenbug

    Greenbug
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    Looks like your first shot was the slowest one (if they are in firing order). Could be as your barrel/chamber heat up you get a velocity jump.
    Any sign of the dreaded carbon ring? Was the barrel/chamber clean when you tested velocity? I notice more these days with the fancy high tech powders that a carbon ring forms and starts messing with velocity, mainly increasing after a certain number of rounds fired.

    I would suspect your old primers may be the culprit. It should be pretty cheap to test that theory.

    Clean your case necks really well with a brush before charging your powder and seating your bullet. Champfer your case mouths as consistently as possible, this helps with velocity consistency too.
     
  3. Dyjital

    Dyjital
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    What rifle.
    Bolt or semi?

    What's the time between shots?
    Are the above in this order for shot string?

    Screen Shot 2019-06-08 at 10.39.51 PM.png

    What I'm looking at is an explanation that would cause a case heat up condition where the powder/primer got warmer than the others from a warm barrel. If this can't be found then I'm going to guess a powder fluctuation or something related to potential neck tension (you stated new 1x brass the neck sized).

    I know powder weights are used, but have you ever dumped powder out and verified it gave you the correct amount the first time?

    What scale? Was there creep in the scale weights? Some scales like to be on 15+ minutes before being used.

    Were the rounds loaded in the order they were fired? Unknown?

    There are a lot of variables that could cause this extra velocity. I have a system when I load, it's also the same as when I shoot. Start from round 1 and go forward. Any inconsistencies in loading process show up this way too.

    When I shoot a batch made group, I randomly pick from the box to give a good randomization of ammo.
     
    Last edited: Jun 8, 2019
  4. DizzyJ

    DizzyJ
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    Following.
    Would definitely check the primers first.

    That powder is fairly temp stable.
     
  5. v0lcom13sn0w

    v0lcom13sn0w
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    TBH if youre shootin them fairly quick, id be pretty happy with those results, personally.

    do they group well?
     
  6. bsa1917hunter

    bsa1917hunter
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    I highly doubt that type of spread is yielding "1/4 minute" accuracy. Just a suggestion here: if you post a picture of a target to go along with a post like this, sometimes you can see a pattern. I'd like to see the 9 shot group. If it were, in fact, 1/4 minute accurate, it would look like 1 hole though. I think we need more info or at least a clarification. I also shoot that particular bullet in 3 AR's and 1 bolt gun and it has proven to be exceptionally accurate out to 450 yards.
     
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  7. Flatfish

    Flatfish
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    Rifle is Tikka T3 heavy bbl 1/8" twist

    Scope-NF 5-20 shv.

    Barrel was cleaned and wiped dry (No oil in bore) before string was shot.

    Rounds were loaded in order fired.

    Velocity listed is the order they were fired in. Lowest velocity is first shot in string.

    String was fired as fast as I could shoot over screens. No rounds were left in hot chamber to heat up before firing. Loaded 2 magazines, fired em back to back. No magazines were left in the sun, or on a dashboard or anywhere else they could heat up past ambient temp (Upper 60s yesterday afternoon). Ammo was from cab of pickup on ride to range. So very close to outdoor temp yesterday.

    String over chrono was simply fired into dirt bank. Not at target. I never stood up, or moved around to alter distance between me & chrono. Just sit and fire while trying not to shoot the screens.

    Had some spread with new, unfired, full length sized cases. But that was 3 shot strings during load development when looking for velocity flat spot "node". My loading procedure is to get velocity window figured first first, then check for accuracy.

    Cases are deburred & chamfered before each loading.

    Bullets are seated within a couple thou of lands. Not touching/jammed into rifling.

    BSA- 1/4moa comes from accuracy testing at tcgc. Shot two groups, 3 shots each, into high .5" at 200 yards. I do not have target. Have not shot off a bench since then. If you would like, I'll meet you there, and you can shoot it. In the mean time, I am looking a gift horse in the mouth, and looking for lower velocity deviation.
     
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  8. DizzyJ

    DizzyJ
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    I applaud you for trying to shrink your spread. I know a rifle can shoot tight groups at closer ranges with big velocity spreads, but as you mentioned, when you start stretching its legs, those groups will open up.
     
  9. Steel Head

    Steel Head
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    Certainly try newer primers.

    Also what dies?
    Annealed?

    Also I’d mark that slow case.
    I always mark cases that give me weird results and cull them if they repeat it.
     
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  10. Dyjital

    Dyjital
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    @Flatfish,
    You certainly have covered all bases except primers.

    And I mean you have all details covered to my liking for taking variables out of the equation, with that said it may be time to experiment with newer primers.
     
  11. Flatfish

    Flatfish
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    Have 10 loaded with CCI BR primers. Same everything. Just a primer swap.
    Sportsmans didn't have 205M. Will try another store or two tomorrow. Hopefully the fix is simple as primers. If not, maybe 205s (If I can find them).

    Thanks for the help everyone!
     
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  12. Flatfish

    Flatfish
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    6-13-19 Update

    Tried same load. Used CCI BR small rifle primers in place of Federal 205M in original load.
    Velocities were (In order of shots fired):
    1-2936 fps
    2-2957 fps
    3-2928 fps
    4-2948 fps
    5-2952 fps
    6-2966 fps
    7-2960 fps
    8-2917 fps
    9-2954 fps
    10-2958 fps

    The good news is, there is an improvement over the older lot of primers. 49fps extreme spread.

    The bad news (In my eyes) is, E.S. is still bigger than I am looking for. I need to take a hard look at my practices, and evaluate each step. There's some wiggle room in there somewhere.

    Have not found Federal 205M at any of the 4 stores I looked at. Seem to be in short supply right now. Will try newer lot once I find em.
     
  13. thorborg

    thorborg
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    And an expanding barrel is of little consideration?
    That would be the first thought I had. So I would shoot my string again cooling between each shot. If same results, then move on. Otherwise, a useful revelation.
    If you change more than one parameter at a time, you'll never come to a proper conclusion.
    Ultimately, the problem with most string data is its an average of the loads you just shot, and they are now gone. It is an insatiable dream sought by nearly every benchresters to achieve perfect repeatability of every round fired. good luck with that.
     
  14. Reno

    Reno
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    Uniform primer holes is your next step to shrink your spread. Different sized holes equals different ignition. And so forth.

    If your getting sub minute results though, why keep messing with it?

    What’s the saying, don’t fix what ain’t broke.
     
  15. Flatfish

    Flatfish
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    Borg- Expanding bbl due to heat. Does this cause higher or lower velocities?

    Reno-Flash holes? Or primer pockets?
     
  16. Reno

    Reno
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    Flash holes.
     
  17. flashpan

    flashpan
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    Head scratcher for sure. Just thinking out loud here. Are you confident your crono is working as it should?
    Be interesting to shoot groups at 600yds also.
     
  18. Flatfish

    Flatfish
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    Chronograph thing crossed my mind. Running a Pact unit ( PC2 if memory serves)from the 90s.

    It shows correct velocities with all other rifles. None of them have deviation swings like this 223 does. Did it thru load development as well. I ignored it, because see little reason to fret over performance of ammo that didn't make the velocity/accuracy cut. In hindsight, it's worth stating.

    Groups at 500 yards are small. Shooting gong from prone (Not off bench), shows clusters under 2" on a regular enough basis to know it's not a fluke. I run out of talent before the rifle does. With someone else on the rifle, it may well improve.

    Last time I shot it off a bench was 200 yards. Groups were about 1/2" then. That's about as well as I can see at that range with the equipment involved.
     
  19. flashpan

    flashpan
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    For long range (In this instance, 500-1000 yards for the sake of conversation), this is gonna cause misses.

    With the ES you have I would have agreed with your original statement above, but If it shoots those small groups at 500 then its a real mystery. How many groups did you shoot at 500? Anything further out?
    Maybe just rejoice?
     
  20. thorborg

    thorborg
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    Higher
     

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