Ballistic "fingerprinting" might not be as foolproof as many once believed - and this could prove a huge headache for prosecutors in criminal trials. A series of tests are to be conducted by leading South African forensic expert David Klatzow.The tests - during which thousands of rounds will be fired into a ballistics tank designed to catch bullets and spent cartridges - follow proposed amendments to the Firearms Control Act.One amendment calls for the country's 4 million legal owners of guns to surrender their firearms for ballistic sampling.The data will then be included on the police's Integrated Ballistics Identification System for comparing gun-related crimes.But the South African Gun Owners' Association said the US National Research Council had noted that the fundamental assumption underlying ballistics "fingerprinting" - that every gun leaves microscopic marks on bullets and cartridge cases that are unique to that weapon - has not been fully demonstrated scientifically as yet.Klatzow said the notion that you can link a bullet to a particular weapon at the exclusion of all others is a fundamental forensics principle that is "now being questioned by forensic experts".Klatzow said that previously the accepted belief was that during the manufacture of a firearm, micro-imperfections were imparted to the barrel and other components that were unique to the weapon."But we now know that a significant quantity - 25% of the marks that match - do so by chance alone."Klatzow said the gun owners' association had asked him to use his expertise and background to determine just how accurately bullets could be linked to a specific gun. He will examine whether the marks on a bullet and cartridge that are produced by a weapon are permanent or subject to variability from shot to shot.He will also compare several weapons to determine the frequency at which random matches might occur."If there are no permanent marks then there is no relevance to government 'fingerprinting' firearms," Klatzow explained.He said the big problem was this applied only to legal firearms."In the US it has been found that almost half of the 'innocence cases' were as a result of faulty, fraudulent and dishonest forensic science."Fort Hare law faculty professor Lirieka Meintjes van der Walt said one of the biggest problems facing the South African justice system was that scientific evidence was seldom properly challenged in court.Said Meintjes van der Walt: "In the US, Canada and Australia, before evidence can be submitted in court it has to comply with scientific methodology. This doesn't happen here in South Africa."Defence attorney Ulrich Roux said: "If the investigation showed firearms do not leave a 'fingerprint', it could potentially have a big impact on prosecutors' cases."Police Department spokesman Musa Zondi said the amendment recognised "a ballistic link does not show or prove by whom the shot has been fired, so it is simply of assistance in the investigation".He said the gun owners' association was within its rights to conduct its own tests...