I have the mailing addie of the french importers into europe of COLDSTEELS bigbore blowguns,they sell a range of darts including mini-broadheads,I was going to order my son one for Xmas when I found out that yes indeed,they are now classed as firearms My old one killed rats at ranges of up to 8-10 yards easily enough,and I have seen bamboo ones used in Borneo which were effective at longer distances,but the bamboo darts were approx 8-10 inches long
No one bothered back then David,I still remember walking past Hector Mouldens garden as a kid when he told me to get my BSA meteor from it