The weapon is being sent to the Forensic Science Laboratory (FSL) here for ballistic tests.
ATS inspector Shabbir Ali Saiyed was playing the role of a terrorist during a mock drill Feb 24 when he was hit by a bullet fired by DCP Trivedi who was leading one of the "rescue" teams.
Saiyed is undergoing treatment at a Surat hospital.
Minister of State for Home Amit Shah, while announcing an inquiry into the incident in the ongoing assembly session, termed it an "accident".
Patel started the inquiry into the incident and recorded statements of police officers and some airport officials who were present at the spot during the time of incident.
Asked for his comments Saturday, Patel said they would await the forensic report before saying anything on the matter.