Trajectory question

Discussion in 'Percussion Rifles' started by brazosland, Aug 21, 2019.

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  1. Aug 21, 2019 #1

    brazosland

    brazosland

    brazosland

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    .54 cal, .530 ball over 80 grns of 3F. This load puts holes in holes about an inch high at 50 yards.

    I assume this ball has already crossed the LOS somewhere around 30 yards and out past 50 it is shortly going to start heading down to cross the LOS again at the “zero” range.

    Correct?
     
  2. Aug 21, 2019 #2

    hawkeye2

    hawkeye2

    hawkeye2

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    Yes, effectively you have 2 "zeros".
     
  3. Aug 21, 2019 #3

    bang

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    Won't know until you shoot 100. Pretty sure +2 at 50 should rise to about +3 at 100, around +1.5 at 175 then falls hard from there to around -2.5 at 200, -12 at 250. Your numbers will be different. The chart I have is for 250gn on 150gn. Barrel length plays in. I would never shoot 150gn charge myself. Sounds like you have a good charge. Stick with what's produces accuracy. +2 at 50 is good start. Just depends on how far you want to shoot. It'd tit for tat. If you hit good over 200 then you are real low aim under that and visa versa. Black powder and its substitutes together with straight bore are pressure limited. Trajectory like throwing a rock.
     
  4. Aug 21, 2019 #4

    brazosland

    brazosland

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    I am just used to flatter lines on the graph!
     
  5. Aug 21, 2019 #5

    bang

    bang

    bang

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    Won't get it with thunder sticks.
     
  6. Aug 21, 2019 #6

    brazosland

    brazosland

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    I teach professionals to hit targets at extended distances, so this stuff is not new. It’s just much, much more slow in terms of how tracks develop.

    I am also used to using height over bore offsets of 3-5 inches...which yields some very interesting near range trajectory numbers. Having the ball exit the muzzle 1/2” under the sight was confusing me for a minute. Still haven’t decided using my Mk1 brain what my near range zero should be...13-18 yards, or 35.

    Anyone have a good BC chart for roundballs?
     
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  7. Aug 21, 2019 #7

    SDSmlf

    SDSmlf

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    Just ran some numbers on a ballistics program I use.

    Assuming your 80 grains of fff gets your .530 round ball to 1600 FPS at the muzzle, you will be 2” high at 40 and 50 yards, zero at 83 yards, and 2.7” low at 100 yards. Also assumed your sight was 0.9” above the center of the bore.
     
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  8. Aug 21, 2019 #8

    brazosland

    brazosland

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    C4CF96EB-245B-48A9-9047-D24332E59044.jpeg FE35D895-62F1-4C3C-9FE3-F928CEB18596.jpeg Thank you, SDSmlf. Bang, those numbers aren’t even close to how a ball is going to fly.

    Going to chrono this weekend, 1600 seems about right.

    Same patch/ball combo over 50 grains is dead on at 50 and very tame to shoot. 80 grns in this 8.5 pound rifle barks a little and bites some too. Texas deer aren't that big so I bet with most of my shots under 60 yards that load will do fine.

    Her name is Margaret. Sweet girl!
     
    Last edited: Aug 21, 2019
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  9. Aug 22, 2019 #9

    Oregononeshot

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    My 54 with a 535 ball and 85 grains of 3f hits 2-3 inches high at 50 and center at 100. No idea of velocity, doesnt matter to me. Haven't shot out past 100 but plan to shoot 125 to check drop. I'm guessing it will be 3-4 inches low
     
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  10. Aug 22, 2019 #10

    SDSmlf

    SDSmlf

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    Took a second look at ballistics program numbers. That 1600 FPS load is 9” low at 125 yards, 19” low at 150 yards, 32.5” low at 175 yards and 51” low at 200 yards. Not sure you could call this a flat shooting load, but that is what the program says. Time for some range time if you really want to know.
     
  11. Aug 22, 2019 #11

    bang

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    Goid grief. I told the only chart I had was a 250gn on 150. But the trajectory woul be rainbow. Now you say you are shooting 60 yards. That's point and shoot. Need some cheese with that?
     
  12. Aug 22, 2019 #12

    dave951

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    Round ball has a horrible BC.
     
  13. Aug 22, 2019 #13

    biliff

    biliff

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    FWIW, RB BC from .32 to .58 runs from .04 to .07. Don't think you get to a .1 until you hit .70 caliber.

    As for near range zero its usually around 12-15 yds.
     
  14. Aug 22, 2019 #14

    Boomerang

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    At least it won't keyhole.:D
     
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  15. Aug 22, 2019 #15

    Phil Coffins

    Phil Coffins

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    My 32” barrel 54 gets 1818 FPS with 110 grains of ffg Goex and gives 1 3/4” groups at 50 yards. Dead on at 100 yards. Off hand the recoil is very manageable from the bench is stout but I don’t hunt from a bench. Its good to be ready for a longer shot should the heed arise.
    With such a pretty rifle like yours them tiny Texas deer will have a hole clean threw them length wise with 80 grain loads.
     
  16. Aug 22, 2019 #16

    brazosland

    brazosland

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    You couldn’t be more right Phil! I put five balls into 2” at 50 with that 50 grain load. The 80 grain load was just slightly bigger at 50.

    On the range teaching Friday and Saturday but Sunday I will have the afternoon to get some dope at 100 behind the house. Thanks for taking care of this rifle until I came along!
     
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  17. Aug 24, 2019 #17

    Rat

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    That's right. You can load it frontwards or backwards, or even sideways the the BC doesn't change.
     
  18. Aug 27, 2019 #18

    Mark Herman

    Mark Herman

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    Everyone is talking high, low and everything in between including velocity. Unless I missed it no one has said where the original, or other, poster is sighted in at to start with. Seems to me that is an important factor in determining rise and drop.
     
  19. Aug 27, 2019 #19

    bang

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    Actually you can look at all the data there is but until you go to the range you will not know what works for your gun or you. Data will give you good idea on the average which is helpful but tje true data is your guns data.
     
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  20. Aug 27, 2019 #20

    renegadehunter

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    The OP said he was hitting 1" high at 50 yards. The absolute best thing to do is shoot it at different distances and find out where it hits and then determine the best zero distance off that data.
    I'm going with a 75 yard zero. My RB load of 80 grains of 3f is 2" high at 50, and about 4" low at 100. Out to a 100 I can just hold a bit under center lungs and its going to do the job. I don't know what happens much after 100, I've limited myself to 100 yards or less.
     

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