Hells Angel Gerry Tobin, who was shot dead on the M40, was targeted with two different handguns, a forensic scientist told a court.
Phillip Rydeard said the bullet recovered from Mr Tobin’s skull was fired from a revolver, while a cartridge case found near his body had been discharged from a self-loading pistol.
Mr Tobin was killed as he made his way home to London after attending the Bulldog Bash bikers festival in Warwickshire.
Mr Rydeard, a firearms specialist with the Forensic Science Service, told Birmingham Crown Court that the round which killed Mr Tobin was a 9mm Luger bullet coated with a jacket of nickel-plated steel.
Giving evidence on the fifth day of the trial of six men accused of murdering Mr Tobin, Mr Rydeard said the fatal bullet, removed during a post-mortem, had been fired from a revolver despite being manufactured for use in self-loading pistols.
He said: “In this particular case the rifling marks were overwhelmingly typical of the marks that are caused by revolvers.”
A spent cartridge case found after the shooting on the M40 in Warwickshire in August last year was shown to the jury by Mr Rydeard.
Questioned by prosecutor Timothy Raggatt, QC, about markings on the 7.65mm cartridge, Mr Rydeard told the court they were indicative of a self-loading pistol, a different type of weapon from the one which was used to fire the fatal shot.
The jury was also shown a rear mudguard removed from Mr Tobin’s motorbike which had a hole in it slightly larger than 7.5mm.
Mr Rydeard said he believed a bullet had penetrated the metal mudguard and “skirted” through the tread of the bike’s rear wheel.
The trial has heard that Mr Tobin, 35, from Mottingham, south-east London, died instantly when he was shot in the head. It is alleged that his killers waited in a lay-by close to a motorway junction near Warwick to select him as a target.
The Crown also alleges that two gunmen from the rival Outlaws gang shot at the Hells Angel after tailing him on the A46 and the M40 as he returned home from the annual Bulldog Bash festival at Long Marston, near Stratford-upon-Avon.
Simon Turner, 41, from Nuneaton, Warwickshire, and 53-year-old Malcolm Bull, from Milton Keynes, are on trial alongside four men from Coventry - Karl Garside, 45, his brother Dane Garside, 42, Dean Taylor, 47, and 46-year-old Ian Cameron.
The full addresses of the defendants, who all deny murder and possessing two shotguns, cannot be published for legal reasons.
Turner and Dane Garside also deny a further charge of possessing a firearm with intent to endanger life.
The case was adjourned until Monday