Matteo Campagna
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A straighter shaft gives tighter impacts

6 studies

ForContextAgainst20142016201820202022202420262014, for, n = 792025, against, n = 592017, for2019, for2015, context2016, context
Each circle is a study: its position gives the year, its row whether it is for, against or context, its size how many participants it measured. Light circles are studies on other populations or without archers.

It depends on how different the shafts being compared really are, and the three direct tests, all by machine, say so clearly. On seventy-nine arrows straight off the production line, shot by machine at twenty-five metres, the group tightens the closer the straightness deviation comes to zero, and straightness plus spine are enough to predict a single arrow's group to within about a millimetre and a half. With a compound at twenty-five metres, aluminium shafts straight to within a thousandth of an inch group in 27 millimetres, bent to three thousandths in 30 and to six in 48, and between two carbon sets of the same model the one straight to within a thousandth groups in 30 millimetres and the one straight to within three in 42. In 2025, by contrast, on fifty-nine Easton X10 shafts all inside factory tolerance and shot at seventy metres, straightness enters no model of the impact point, and the authors explain why: those shafts were far straighter than the tolerance required, 0.007 mm on average with a maximum of 0.015 mm against the 0.025 mm declared. Read that way the contradiction may be only apparent, that is, within a modern competition set straightness does not vary enough to matter, while between shafts of different grades it might. The 2017 test, which compares shafts of different grades, points that way, and all the 2025 shafts lie below the straightest level tested then; nobody, though, has run the comparison with archers shooting rather than with a machine, and in the compound test the choice of nock changed the group more than straightness did, from 44 to 27 millimetres on the same straight shafts. The surrounding evidence is coherent: across ten mid-range carbon shafts the deviation runs between ten and a hundred micrometres, and back in 2015 the person who measured them wrote that the effect on flight was not demonstrated.

Also phrased as: "arrow straightness matters"; "shaft straightness tolerance"; "straighter shafts group better"; "how much declared straightness matters"; "higher grade arrows and grouping"

In practice

Straightness is the first figure anyone looks at on the box, and a tighter tolerance is taken for granted to be worth its price in grouping.

Evidence

  • 2014
    For Equipment tests Published later

    Seventy-nine arrows fresh off the production line, three shots each at twenty-five metres with the nock turned by a hundred and twenty degrees: in the response surface the triangle's spread falls the closer the straightness deviation comes to zero, and a neural network with straightness and spine as its only inputs predicts that spread with test root-mean-square errors of 1.71, 1.51 and 1.52 mm. These are graphical trends with no coefficients, the units of the two construction measures are not made clear in the text, and the journal is a regional one.

    A Study of Arrow Performance using Artificial Neural Network · Yeongsang Jeong, Sungshin Kim

  • 2015
    Context Equipment tests Published later

    Ten mid-range carbon arrows measured to a precision of five micrometres: the deviation from straightness runs between ten and a hundred micrometres, with a mean of fifty-five. The author writes that the effect of this deviation on flight is not demonstrated. It serves to set the scale of the quantity under discussion.

    Applications of Physics to Archery · H. O. Meyer

  • 2016
    Context Equipment tests Published later

    Experimental shots with a 9.7 g cane replica arrow, fletched with three feathers from small birds, softer than turkey feathers: the flight is judged stable and free of visible oscillation even with a shaft that is not fully straight. It is an observation by eye on a few shots, with no measurement of grouping, and the equipment has nothing in common with a competition shaft.

    Archery by the Apaches – implications of using the bow and arrow in hunter-gatherer communities · Žiga Šmit

  • 2017
    For Equipment tests Published later

    A 240 N Hoyt Pro Comp Elite compound on a shooting machine at 25 m, four arrows per set and ten shots per arrow, with the group measured as the diameter of the smallest circle containing every hole. Easton X7 2315 aluminium shafts straight to within a thousandth of an inch and then deliberately bent: with vanes at 0.9 degrees the group goes from 27 mm to 30 mm at three thousandths and 48 mm at six; with straight vanes from 39 to 48 mm, with vanes at 2.1 degrees from 20 to 28 and 40 mm. Between two carbon sets of the same model, the LightSpeed 3D, straight to within one thousandth, groups in 30 mm against 42 for the LightSpeed straight to within three. No statistical analysis, and on the same straight shafts the nock affected the group more than straightness did, from 44 to 27 mm.

    Effect of arrow shaft straightness on arrow grouping · James L Park, Patrick J Aitchison, Adam J Bielby, Vincent Bleakley, Trent P Carberry, Richard M Ellis, Richard D Kerner, Andrew D MacDonald, Danie Oosthuizen, Scott B Pankhurst, Konstantinos Psarakis

  • 2019
    For Review Published later

    A review of how the air acts on target archery: it recalls shooting-machine tests in which straighter arrows group better and spin in flight reduces group size. The figures are not reported in the review, so it counts as an indication of direction rather than as a measurement.

    The impact of the atmosphere on target archery · James L Park

  • 2025
    Against Equipment tests Published later

    Fifty-nine Easton X10 shafts in spine 325, measured one by one and then shot by machine at seventy metres indoors: of the eight parameters in contention, straightness and diameter enter none of the models of the impact point, because they vary too little from shaft to shaft. The measurements show it: straightness 0.007 mm on average with a standard deviation of 0.002 mm and a maximum of 0.015 mm, against a declared tolerance of 0.025 mm, and diameter 5.616 mm with a standard deviation of 0.022 mm.

    Improving the arrow selection process in archery: the stiffness variation pattern matters · A. Kuch, P. Laguillaumie, F. Durand, J.-F. Debril, T. Monnet

Status history

  1. 2014 Reported The first figures come from seventy-nine arrows from the same production run shot by machine: the group tightens the closer the straightness deviation comes to zero, and straightness plus spine are enough to predict a single arrow's group to within about a millimetre and a half. It is a graphical trend with no coefficients and no statistical tests, in a regional journal, hence reported.
  2. 2015 Reported A measurement on ten mid-range carbon shafts gives the order of magnitude being discussed, a deviation between ten and a hundred micrometres, and the person who made it writes that the effect on flight is not demonstrated. This is not contrary evidence, it is a reminder that the quantities involved are small: the status holds.
  3. 2016 Reported The only datum of the year is an observation on a cane replica arrow, which flies stably even though the shaft is not perfectly straight. It is a judgement by eye on a few experimental shots rather than a measurement of grouping, so the question stays as open as before.
  4. 2017 Reported A machine test does what the others had not: it takes aluminium shafts straight to within a thousandth of an inch, about twenty-five micrometres, and bends them to three and six thousandths. With a compound at twenty-five metres the group goes from 27 to 30 millimetres and then to 48, and the same trend shows with straight vanes and with more steeply angled ones; between two carbon sets of the same model, the one straight to within a thousandth groups in 30 millimetres against 42 for the one straight to within three. The direct studies in favour become two and none goes against, but the first is a graphical trend in a regional journal and the second measures one group per configuration, without statistics, and finds that the nock matters more than straightness: the status stays reported, on a broader footing.
  5. 2019 Reported A review by the same author goes back over the machine tests in which straighter shafts group better and spinning the arrow tightens the group. It summarises work already recorded, with no new figures, so the status holds.
  6. 2025 Contested The picture reverses. On fifty-nine Easton X10 shafts all inside factory tolerance, shot by machine at seventy metres, straightness enters no model of the impact point, and the reason is written into the study: those shafts were far straighter than the tolerance required. The direct studies therefore point in opposite directions, two in favour and one against, and the status becomes contested, with the caveat that the contradiction may come from the range of straightness explored rather than from the phenomenon: the 2017 work, with shafts of different grades, finds the effect, while the shafts in this study are all straighter than the best level tested then.

Related

Related articles

Research lines

Cite
APA

Campagna, M. (2026). A straighter shaft gives tighter impacts (Version 2). In Evidence Registry. Retrieved 16 October 2026, from https://matteocampagna.com/en/registry/equipment/shaft-straightness-impacts

BibTeX
@misc{campagna2026_rettilineitaastaimpatti,
  author = {Campagna, Matteo},
  title = {A straighter shaft gives tighter impacts},
  year = {2026},
  howpublished = {Evidence Registry, matteocampagna.com},
  url = {https://matteocampagna.com/en/registry/equipment/shaft-straightness-impacts},
  note = {Version 2; accessed 2026-10-16}
}

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