Havent read the book but almost positive they are illegal to hunt with in the US, prob most of the world, and i think carrying custom versions that dont meet the enforced specs means a hefty fine, but if youre looking for protection this place carries em for Biller shafts but just meet the thread size and youre good to go,
AB Biller Spearguns and Accessories
But def dont use em to hunt,and especially any conditions where you might be passing the speargun to other people or into and out of a boat, there are no safeties, and basically its a loaded bullet stuck to the end of your shaft. Unless youre in the business of fending off large sharks i wouldnt recommend it at all.
