What Ashby measures, and who reads him

Two libraries

The Danish bowhunters’ federation keeps a reading list for anyone preparing for the bow exam. It holds seven documents. Four are what you would expect: the legislation, the state-commissioned reports on the bow’s effectiveness, a note from the veterinary institute. The fifth is a German forensic medicine thesis. The last two are reports signed by Ed Ashby.

We looked for that name in everything we had read for the guide so far: the Swedish council’s 2021 opinion, the two Danish state reports of 2021 and 2022, the Danish animal ethics council’s 2017 letter, the European hunters’ federation position, and the studies all of those cite. It is not there. Not once.

That does not mean the people who write the law have not read him — we cannot know, because we read the documents rather than every bibliography. It means something else, which can be checked: what bowhunters read and what lawmakers read are two different libraries. For a moment, the literature list puts them on the same shelf.

We read six of the forty-one reports on his site. What follows is what is in them, what can be used, and what cannot.

What he actually measured

The foundation is a project at the Mkuzi reserve in Natal, South Africa, begun by the chief ranger there, Tony Tomkinson. Natal Study gives the account: 32 types of broadhead, tested on impala, bushbuck, warthog, nyala, wildebeest and zebra — giraffe and rhino were tested and then left out of the analysis. The bows were chosen so as not to limit the outcome: an 80-pound compound and a 94-pound longbow. The analysis rests on 154 consecutive shot records.

The data come from two places: animals hunted with the bow, and — where a closer evaluation was wanted — animals first taken with a rifle, with care not to touch tissue near the site of the test shot, then positioned and shot with an arrow. Every shot was evaluated by dissection. The criterion for a lethal hit is written out: a major nerve centre penetrated, a major vessel severed, the thorax penetrated with a vital organ struck, or a major visceral organ hit.

The rule that holds the whole thing together is one of freshness, repeated in the 2024 update: every shot on a downed animal is taken within thirty minutes of the animal’s death. The reason is physiological. In living tissue the muscle fibres retract as they are cut and open the wound channel, and blood lubricates; once flaccidity sets in, none of that is true any more. For the same reason he rejects ballistic gelatine, which was made for the cavitation a bullet produces.

The figures that hold

Lethality by hit location, irrespective of broadhead, is the most useful part. The quartering-away shot was lethal in 24 cases out of 25. The neck-shoulder junction, approached from a forward quartering angle, was lethal in 51.5% of cases — the hardest shot in the table. The rump, a little over half.

Then a line that has to be read carefully, because it is easy to misuse: the broadside shot into the chest-shoulder area, the one considered classic, was non-lethal in almost 30% of cases. Taken alone, the figure seems to say that the broadside angle is a poor one — which would contradict the Danish data, where 454 of 576 shots at roe deer were broadside. But the source says why they failed: every failure came from inadequate penetration, generally from the broadhead giving way. One of the observations at the start of the same report is that many of the 32 heads tested bent or broke even without hitting bone. The figure is not about the angle. It is about the equipment.

The largest difference in the study is between single-blade and multiblade heads. At the neck-shoulder junction — the hard shot — single-blade heads were lethal in 17 cases out of 20, and multiblade heads in none out of 16. Where a rib was struck on entry, a single blade gave ten lethal hits out of ten. The author notes an imbalance himself: most of the multiblade shots at the neck-shoulder were taken on light animals, while eight of the seventeen lethal single-blade hits were on wildebeest, the heaviest-boned animal in the test.

What he says about his own data

This is the part that decides how far he can be taken. In the series introduction he writes, without being asked, that his texts contain “many verified facts and numerous inferences (things suggested by the data, but not verifiable at a statistically significant level)”, plus personal opinions that he says he will endeavour to identify as such.

That is a more honest declaration than most people make, and it is exactly the distinction we require of ourselves on the country pages. But it means that part of the corpus cannot carry a legal threshold, however well it reads.

One more report is worth mentioning for its own reason. The 2007 report is written entirely to correct the way his own data had been misused: someone had lifted a chart out of context, without the text that went with it, and presented it as proof of the opposite. It is, literally, a case from the family described in “How a number travels” — told, this time, by the author of the data.

The sentence that collides with European law

Of the twelve factors, the sixth is arrow mass. There, in a paragraph that is not about mass, sits the most awkward sentence in the whole corpus: kinetic energy “should be used as neither guideline nor requirement” for terminal arrow performance, because it does not predict tissue penetration and, by definition, is not a measure of an arrow’s force.

Denmark regulates in joules. Finland, Hungary and Slovakia regulate the bow’s draw weight, in newtons. The figures are on each country’s page in the guide and are not repeated here. And the two factors he ranks first — the structural integrity of the whole system and the quality of arrow flight — appear in no European legal text we have read.

We are not saying he is right. We are saying what can be checked: if he were, then Europe regulates the bow, not the arrow. And if he is not, nobody has yet written down why not.

Support from an unexpected quarter

The fifth document on the Danish list, the German forensic medicine thesis, is a doctorate defended at Münster in 2004 whose essential parts appeared in the Journal of Trauma. An institute of forensic medicine, with no connection to bowhunting and nothing to defend. The Münster thesis arrives, by an entirely different road, at two of Ashby’s conclusions.

First: gelatine and soap, the standard media for testing firearms, are not suitable for arrow wounds. Penetration depths differed markedly between the two media and, above all, from real tissue. And in tissue the sharp heads penetrated deeper than the blunt ones — the reverse of what the simulants showed. The test medium was not merely getting the value wrong; it was inverting the order. Ashby rejects ballistic gelatine for exactly the same reason, with thirty years of shooting at animals behind him; the Germans got there with a light barrier and four pigs.

Second, and more interesting: in soft tissue the arrows penetrated about as deep as pistol bullets — which means, the authors write, that for the same depth an arrow needs only a fraction of a bullet’s kinetic energy. That is not the same as saying kinetic energy predicts nothing. But it is an academic measurement, published in a medical journal, showing that the relation between joules and what happens inside the animal is not the one a law written in joules assumes.

What cannot be carried across

The animals are Cape and Asian buffalo, elephant, hippo, zebra, wildebeest. The 650-grain threshold of arrow mass, below which the chance of breaching heavy bone drops markedly, is calibrated on them. Moved to roe deer, it would be the same error we have already caught in a Norwegian model built on bullet impact and then used for arrows: an instrument made for one context, applied to another. The test bows, at 80 and 94 pounds, are not the bows roe deer are hunted with in Europe.

The framing is avowedly campaigning. The introduction says plainly that bowhunting has long been a target of the anti-hunting movement and that the only defence against misinformation is verifiable fact. It is honestly said, and it is a position many readers of this journal share — but an authority will weigh the text as a position, not as neutral science. Two of the links on the reports page lead to a retailer selling arrows built on his principles; the author states, in the series introduction, that he has never held any affiliation with any archery company and that every project apart from Natal Study was funded out of his own pocket. We report both.

And one small drift, inside his own corpus. The 2019 update says the last decade’s data come “on over 1700 buffalo, 96 elephant”. The 2024 text, with the same figures, says “over 1700 shots on buffalo, 96 shots on elephant”. One animal can take more than one arrow; they are not the same thing. We do not know which wording is the correct one, and so we do not use the figure either.

What we think

What follows is opinion, not finding.

We are less interested in whether Ashby is right about each of the twelve factors than in what the existence of the two libraries shows. A bowhunter in Denmark studies for the exam from a list that includes these reports. An official writing an equipment threshold reads something else entirely. The two sets of texts do not contradict each other — they do not even hear each other.

That explains, we think, part of what European bow legislation looks like: it regulates what can be measured easily before the shot, the bow’s draw weight and the arrow’s energy, because those can be written into a ministerial order and checked at an exam. Structural integrity and quality of flight are harder to put into an article of law. We are not saying anyone decided this; we are saying that this is what the result looks like.

What ought to be done is less dramatic than it sounds. Not to translate Ashby into law, but to have someone with no interest in the outcome measure whether the things he names matter as much as he says they do, on European animals and with European bows. Until then the reports remain what they are: the largest collection of penetration measurements on real animals that exists, made by one man, who marked his own inferences himself.

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