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Thread: How much of a difference does 20 grains make?

  1. #1
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    How much of a difference does 20 grains make?

    Hi gang.

    On a recurve bow, how much does 20 grains make a difference on tune? I am asking this because I shoot 410 x10s with 120 grains points with good tune. But now that it's indoor time, I need to roll with 100 grain points, as Easton only makes 100 grain points for the X7 aluminums. If I went to 100 grain points, does anybody know which spine arrows I should order? I was thinking of going with 450s.

    My draw length of 30 inches, if that helps.



    Thanks


  2. #2
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    what's the rest of the setup? lacking way too much info.

    Is that DL AMO ? How did you measure..

    DW?
    The Sticky "What to include"

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    It's the Indian, not the arrow!

  3. #3
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    Of course 18M is very close (relatively speaking) so tune is not going to be quite as important.

    DC
    The Sticky "What to include"

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    It's the Indian, not the arrow!

  4. #4
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    TRB -

    In VERY general terms, 20 grains up from = ABOUT 2# of dynamic spine; 20 grains at tail = ABOUT 4 grains of dynamic spine but in the opposite direction. Depending on the speed of the bow and your shooting ability, the 20 grains may or may not show a difference in elevation due to weight.

    dchan is correct, 18M/20 yds usually doesn't require a perfect tune.

    IF we assume the 410's spine/tune correctly at 30", you're looking at a 2214 or 2311 in X7.
    That also assumes you're shooting a bow close to 50#.

    Viper1 out.
    “Simple and innocent, however, as it (the bow) appears, and capable as it is of being a trusty friend and ally, a bow is at the same time a watchful enemy, ready to take advantage of the smallest slight.”

  5. #5
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    DL is from nock grove to the clicker. I am shooting 47 pounds right now. Arrows are shot from Ex Primes + CXT.

  6. #6
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    I wouldn't say I'm super good, but I'm confident that I'm consistent enough so that my tuning is "accurate".

  7. #7
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    Quote Originally Posted by TheRohBoat View Post
    DL is from nock grove to the clicker. I am shooting 47 pounds right now. Arrows are shot from Ex Primes + CXT.
    DL should be measured from a fixed point not a clicker.

    AMO DL is nock grove to 1.75" past the pivot point of the grip (or on most bows the center of the plunger hole)

    Is the DW measured, marked or calculated?
    The Sticky "What to include"

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  8. #8
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    I shot 30#@30", and used cartel triple arrows, sized 550 maybe (cannot quite remember). At 30-40 yards, 20 grains made a huge difference on spread, 2 to 3 times the spread diameter.

  9. #9
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    Quote Originally Posted by xm8k36d View Post
    I shot 30#@30", and used cartel triple arrows, sized 550 maybe (cannot quite remember). At 30-40 yards, 20 grains made a huge difference on spread, 2 to 3 times the spread diameter.
    Missing way too much information to get any reasonable data from this but if we take your data at face value,

    your arrows (cartel triples) should have been in the 850 range. So shooting 3-4 spines stiff, they will be very unforgiving to anything (including weight) especially getting out to 30-40M.
    The Sticky "What to include"

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  10. #10
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    I'm not sure about AMO DL. I've always measured DL from the clicker to the nock grove. But my clicker is at exact halfway of the clicker extension on my riser, so I would say that 30" is close to AMO DL. Kinda unscientific, but that's my measurement for now. I currently (like at this moment) do not have a method to accurately measure DL. Would you suggest 450 for X7s?

  11. #11
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    Quote Originally Posted by TheRohBoat View Post
    I'm not sure about AMO DL. I've always measured DL from the clicker to the nock grove. But my clicker is at exact halfway of the clicker extension on my riser, so I would say that 30" is close to AMO DL. Kinda unscientific, but that's my measurement for now. I currently (like at this moment) do not have a method to accurately measure DL. Would you suggest 450 for X7s?
    With out more accurate numbers its hard to make anything other guesses. Is your draw weight measured, marked or calculate? It all makes a difference. Since so much depends on the shooter as well. More info including demographics for you as an athlete.

    DC
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    It's the Indian, not the arrow!

  12. #12
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    Why is it exactly you need 100 grain points for indoor?
    And easton actually makes, or at least used to make 100 grain points since I shoot those outdoors. http://www.eastonarchery.com/products/accessory/406
    I'm a guy, just so you know

  13. #13
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    Take a bow square and place it on your rest as though it were an arrow and place the clicker over it. Measure the distance from the button centre to where the edge of the clicker closest to the shooter lies on your measuring tool. If it is above 1.75", subtract the excess from your total arrow length and you have your AMO draw length. If it is less than 1.75" add the difference to your total arrow length to get AMO draw length.

    E.g. if you measure the distance between your button and clicker as 2", and your arrows are 30" from throat of nock to tip of point, you must subtract 0.25 inches to get your AMO draw length, in this case 29.75".

    On the other side, if you measure the distance as 1.5" and your arrows are 30" from throat of nock to tip of point, you must add 0.25" to get your AMO draw length. In this case 30.25".

    Basically the only way your draw length corresponds to your arrow length, is if the clicker falls 1.75" from the centre of your button. (unless I am mistaken about the centre being the correct place to measure from.)
    Inno CXT
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  14. #14
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    I think 30 inches is right for AMO length, although I will try and use the method that anmactire mentioned.

    As for demographics:
    -draw weight is measured
    -I used to shoot about 500-600 arrows a week, though school is getting in the way now
    -I shoot about 410-420 out of 450 usually
    -5'11", medium build... am I missing anything?

  15. #15
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    Coach Dchan included in his signature, 'What to Include' Fill it in completely and then ask the questions again.
    DAS Elite 64" 35lbs - Masters Barebow
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  16. #16
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    Quote Originally Posted by TheRohBoat View Post
    I think 30 inches is right for AMO length, although I will try and use the method that anmactire mentioned.

    As for demographics:
    -draw weight is measured
    -I used to shoot about 500-600 arrows a week, though school is getting in the way now
    -I shoot about 410-420 out of 450 usually
    -5'11", medium build... am I missing anything?
    410-420 out of 450? Distance and target size?

    In any case. I agree with Viper.. 2214 or 2311 x7 ahould be close enough. Again 18M doesn't require a perfect tune.
    The Sticky "What to include"

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  17. #17
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    If we presume 450 round is vegas 3 spot, 45 arrows, then 410-420 means probably shooting 4.5" -5" groups.

    Just getting some perspective.

    Since you are also talking about switching for indoors you will probably switch from vanes to feathers further changing the setuo. They are heavier than vanes. Usng vipers "very general terms" adding 20 grains to the back is like removing a lot more from the front.. So use the 2214 or 2311 as a starting point..
    The Sticky "What to include"

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    It's the Indian, not the arrow!

  18. #18
    I have much easier solution.....shoot your X-10 indoor

  19. #19
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    Thanks coach for your input. Appreciate it. I'll give that a try.

  20. #20
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    Quote Originally Posted by Viper1 View Post
    TRB -

    In VERY general terms, 20 grains up from = ABOUT 2# of dynamic spine; 20 grains at tail = ABOUT 4 grains of dynamic spine but in the opposite direction. Depending on the speed of the bow and your shooting ability, the 20 grains may or may not show a difference in elevation due to weight.

    dchan is correct, 18M/20 yds usually doesn't require a perfect tune.

    IF we assume the 410's spine/tune correctly at 30", you're looking at a 2214 or 2311 in X7.
    That also assumes you're shooting a bow close to 50#.

    Viper1 out.
    Viper,

    In reference to the highlighted text, was that supposed to read "About 4# of dynamic spine?


    Bob Furman
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  21. #21
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    Quote Originally Posted by dchan View Post
    Missing way too much information to get any reasonable data from this but if we take your data at face value,

    your arrows (cartel triples) should have been in the 850 range. So shooting 3-4 spines stiff, they will be very unforgiving to anything (including weight) especially getting out to 30-40M.
    Thanks.
    Cartel has a different system for spines, so whatever I have is fit for 30-35 pounds at my DL. So they could be a bit stiff for me. With 110 or 120 grain point (I cannot be sure, since Lancaster listed confusing information about the full weight of these points), I was able to get some kind of pattern at 35 yards... Lack of practice made it difficult for me to specify my spread.

  22. #22
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    Quote Originally Posted by xm8k36d View Post
    Thanks.
    Cartel has a different system for spines, so whatever I have is fit for 30-35 pounds at my DL. So they could be a bit stiff for me. With 110 or 120 grain point (I cannot be sure, since Lancaster listed confusing information about the full weight of these points), I was able to get some kind of pattern at 35 yards... Lack of practice made it difficult for me to specify my spread.
    Not sure how you figure the "different system"? TAP and most of the other ballistics programs take real data from surveys as well as measured data and mfg published data to build their databases. TAP suggests your ideal model arrow from cartel as 850. If I input carbon express or easton, we would get different numbers.

    GT and limbwalker could probably confirm this but IIRC even the easton charts have a lot of the spine info derived from data collected from the field. Thats why as you get to the middle of the poundage ranges the charts are more accurate. As you get out towards the edges (light and heavy) they are not as accurate. There is less data to pull from so its not as accurate.

    Another thing to consider is that at the lighter weights you had less experienced shooters so a lot of variance can be less then ideal releases and esperience.
    At the heavier weights you have the opposite problem. People that may be over bowed inputing faulty data.
    The Sticky "What to include"

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    It's the Indian, not the arrow!

  23. #23
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    Quote Originally Posted by Ar-Pe-Lo View Post
    I have much easier solution.....shoot your X-10 indoor
    I saw that a local archer shot a much higher score on a second indoor tournament just a month after the first. The difference was that he switched back to his X10s, because his indoor arrows were troublesome for him.

  24. #24
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    Quote Originally Posted by dchan View Post
    Not sure how you figure the "different system"? TAP and most of the other ballistics programs take real data from surveys as well as measured data and mfg published data to build their databases. TAP suggests your ideal model arrow from cartel as 850. If I input carbon express or easton, we would get different numbers.

    GT and limbwalker could probably confirm this but IIRC even the easton charts have a lot of the spine info derived from data collected from the field. Thats why as you get to the middle of the poundage ranges the charts are more accurate. As you get out towards the edges (light and heavy) they are not as accurate. There is less data to pull from so its not as accurate.

    Another thing to consider is that at the lighter weights you had less experienced shooters so a lot of variance can be less then ideal releases and esperience.
    At the heavier weights you have the opposite problem. People that may be over bowed inputing faulty data.
    I think that at the light end of the spectrum there's another problem besides the inexperience of the archers. The charts don't adjust for limb construction. Someone shooting glass/wood limbs is going to need a lighter spine than someone shooting carbon/synthetic core limbs because the lighter limbs accelerate the arrow faster. (More of the force of the limbs is spent accelerating the limb mass.)

  25. #25
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    My 2cents..why not just shoot with your arrows now.
    They are tuned. Plus more $$ in you pocket

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