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Accuracy or Velocity. Choose.

Discussion in 'Rifle Country' started by D.B. Cooper, Jul 13, 2019 at 3:21 AM.

  1. D.B. Cooper

    D.B. Cooper Member

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    Choose. But choose wisely.

    I'm putting together a load for caribou for my 243 Winchester using an 85 grain Barnes TSX HPBT (not the tipped) projectile and Hodgdon Superperformance powder. I need to choose between the most accurate load or the fastest load.

    My best accuracy was about 1/2 MOA from 42.7 grains. That's near the starting charge of 41.2 grains. I didn't have a chronograph then, so I don't know the velocity, but I estimate it to be about 2900 fps. (I seem to gain or lose about 75 fps for every 0.5 grain change in powder charge.) Next-best accuracy was just over 1 MOA from 43.7 grains at 3052 fps.

    Barns recommends a terminal velocity of at least 2000 fps for proper expansion. According to my ballistics calculator, the 2900 fps load drops to 2000 at 350 yards and is still supersonic at 850 yrds.; the 3052 fps load (is 150 fps even enough to worry about?) drops to 2000 fps at 400 yards and is still supersonic at 900 yards.

    SO...the slower, more accurate charge works out to be a max effective range of 350, and at 350 and half MOA, that's a roughly 1-3/4 group. (I'm not that good of a shooter to hole 1/2 MOA from a field position.) The kill zone on a caribou is roughly 12-14 inches.

    The faster, less accurate charge works out to be a max effective range of 400 yards, and at 400 and just over 1 MOA, that's roughly a 4" group.

    Just from typing this up and re-reading it, I'm wondering if there is enough difference between these two to make a difference. Both are probably sufficient for my purpose. (Neither are what I would call stellar.) I also have to ask myself if I would even shoot a caribou at 350 or 400 yards.

    Anyway. Tanks for reading my lengthy post, and I look forward to hearing your thoughts.
     
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  2. mdThanatos

    mdThanatos Member

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    I'd go with the more accurate load in this situation, just to increase the chances of a good hit, if you were to shoot one at that distance. I don't think there is enough difference between the two distance and velocity wise to outweigh the group sizes that you are estimating.
     
  3. LoonWulf
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    LoonWulf Contributing Member

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    my requirements in terms of accuracy and velocity are 1-1.5moa, and very nearly top velocity.
    I'll switch components till I get what I'm looking for.

    of your two loads I'll always take velocity as long as accuracy is acceptable for your intended purpose.
    Barnes has data upto 3300 fps for the 85tsx, and superformance.
     
  4. D.B. Cooper

    D.B. Cooper Member

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    Yeah. And in my rifle, those max loads shoot terrible. 2-3 MOA.
     
  5. Alaskan Ironworker

    Alaskan Ironworker Member

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    Either load sounds entirely adequate for your purpose. I would suggest investing your time in jogging rather than chasing the last bit of accuracy out of your rifle. Your fitness will serve you better in the field, and it seems many hunters forget about that aspect of the hunt.
     
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  6. D.B. Cooper

    D.B. Cooper Member

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    Amen to that. And I'm already behind the curve.
     
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  7. LoonWulf
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    LoonWulf Contributing Member

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    I'd be switching components at that point, but again that's my methodology.
    For what you want I'd still probably take the highest velocity load that gives acceptable accuracy. In my limited experience (mostly watching other folks, I never had good luck with monometals) the monometals do best when impact velocity is kept as high as possible.
     
  8. forty_caliber
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    forty_caliber Contributing Member

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    The choice is pretty obvious...the lower power more accurate load is the one to go with. 2900 fps will get the job done. Thin skinned game and shot placement will be key at any distance.

    Caribou sounds like a hunt of a lifetime. I wish I could go with you. :)

    .40
     
  9. BigBore44

    BigBore44 Member

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    I would change powders. Doesn’t sound like the Superformance is living up to its name. But that’s me.

    How good of a Hunter are you? How slow can you move without being seen by white tails? The better hunter you are, the less you need the higher velocity.

    You’re also only talking 150fps difference in the two loads. Not monumental by any CF rifle standards.
     
  10. jmr40

    jmr40 Member

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    This is my approach. If I can't get BOTH velocity and accuracy that meet my requirements I try something else until I do.
     
  11. Demi-human

    Demi-human Member

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    I estimate that you could be way off, or not. Maybe...

    I know, "Every rifle is a law unto itself." and that I know only my laws, but that seems like a large velocity spread for two and a half grains of powder.
    Check them, now that you have a chronograph. There might not be a big difference, since stated the maximum loads were terrible, these may be closer together than the books say.

    I concur. (sigh) Someday...

    But with a Thirty Aught Six!:D
     
  12. JT-AR-MG42

    JT-AR-MG42 Member

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    Absolutely in agreement.

    JT
     
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  13. Nature Boy

    Nature Boy Member

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    Me too.

    I’m a fool for accuracy though, so I’m always going to chasing the optimized load first with velocity/energy second

    I have an accurate (5 shot 1/2 MOA) .308 load with 180g Nosler BTs but it’s only traveling at 2,500 fps. I’ve killed deer with this load so I know it works, however, I keep experimenting trying to find that higher node. Unfortunately I get pressure signs before I get accuracy.

    I have 4 more bullets to try so the search continues. No real reason for doing it other than it’s part of the enjoyment and satisfaction that comes from knowing you taking the best ammo you can make to the field that’s tuned for that rifle
     
  14. jmorris

    jmorris Member

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    With a G1 of .333 starting at 3052fps you are at 2907 by 50 yards.

    So would you take a 50% hit in accuracy to retain velocity an extra 50 yards?

    I wouldn’t.
     
  15. Hookeye

    Hookeye Member

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    Cranked and under 1.5 at 100......run it.
     
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  16. murf

    murf Member

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    reliability is most important when going on a hunt. don't neck size your cases, don't jam the bullet into the lands, etc. accuracy is second if you are going to shoot long ranges from a field position and velocity is a distant third as you should limit the distance of your shot to the required remaining energy that will down your prey.

    luck,

    murf

    p.s. I agree that you should change powders.
     
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  17. hillman23

    hillman23 Member

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    Considering your either/or proposition, I would think about which gives you the greatest confidence behind the rifle. You don’t want to be worrying about your gear when your opportunity presents itself
     
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  18. cheygriz

    cheygriz Member

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    I decide what level of accuracy is needed, and work up the highest velocity that will give that level.

    you don't need 1/4 MOA to shoot big game.
     
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  19. skeeterfogger

    skeeterfogger Member

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    A velocity that's accurate, duh!
     
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  20. IndianaBoy

    IndianaBoy Member

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    No honest person is shooting 1/2 MOA from field positions.

    Nor should they be shooting far enough that the difference between 1/2 MOA and 1 MOA for their hunting ammunition should make a difference, not if ethics are a concern.

    I would suggest that the correct answer is whichever one you can afford to spend more time with shooting with high crosswinds, if long distance shots on game animals are a high probability.


    The margin of error in estimating wind drift between a 5 to 10 mph wind is going to have significantly more effect than an additional 1/2 MOA of dispersion between one load or another.

    1 MOA is more than sufficient for hunting ammunition.

    Load it up, zero on a windless day, and then spend some time practicing with sufficient crosswind to push your bullets on a target big enough and far enough away to chart the effects.

    A kestrel wind meter helps. But they aren't magic. The wind is rarely consistent from point A to point B.
     
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  21. D.B. Cooper

    D.B. Cooper Member

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    I think it's called "Superperformance" because I don't see any other powder driving projectiles this fast.

    That's a fair question. It's completely open ground with no cover for miles. 300 yard shots are routine.

    I'm kind of thinking that myself. I need to make up some more of that load and go chronograph it.
     
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  22. IndianaBoy

    IndianaBoy Member

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    You don't need a chronograph.

    Zero at a known distance, observe your real world drop at a distance such as 400 or 500 yards, and punch the data into Strelok Pro.

    It will give you your calculated muzzle velocity and without the potential % error that some chronographs have.

    You will also need to know the twist rate of your rifle. The ballistic coefficients of all major bullet manufacturers are already loaded in the databases within Strelok Pro.
     
  23. D.B. Cooper

    D.B. Cooper Member

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    Many of you have said change powders. I have a limited opportunity for that at this point. Season opens in 26 days, and I have a lot on my calendar between now and then. I have some 4895 on hand, which has worked extremely well in this rifle in the past, with much lighter bullets. So I can put together a batch for testing, but as far as buying a bunch of powders and doing a lot of range trips before opener, that's not in the cards right now.
     
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  24. D.B. Cooper

    D.B. Cooper Member

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    Yeah. That looks pretty impressive.
     
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  25. Garandimal

    Garandimal Member

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    For Mono-metal bullets - speed kills.




    GR
     
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