https://matteocampagna.com/en/registry/equipment/shaft-straightness-impacts Changes to this claim in Matteo Campagna's evidence registry: its status, its year-by-year history, revisions of the page. en-gb https://matteocampagna.com/en/registry/equipment/shaft-straightness-impactsIt 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.claim:rettilineita-asta-impatti:revision:2026-08-13:2Thu, 13 Aug 2026 08:00:00 GMT https://matteocampagna.com/en/registry/equipment/shaft-straightness-impacts#storiaA 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.claim:rettilineita-asta-impatti:history_entry:2026-08-08:2017Sat, 08 Aug 2026 08:00:00 GMT https://matteocampagna.com/en/registry/equipment/shaft-straightness-impactsclaim:rettilineita-asta-impatti:new_claim:2026-06-01:contestatoMon, 01 Jun 2026 08:00:00 GMT