Stanley Metcalf was found fatally injured at a property on Church Lane in Sproatley, East Yorkshire, on July 26.
The boy, who police said was visiting family, was taken to Hull Royal Infirmary, where he died at around 5.30pm the same day.
An inquest into his death was opened and adjourned at Hull Coroners Court on Monday.
No family members were present during the brief hearing, during which senior coroner Professor Paul Marks was told that a post-mortem examination carried out on July 30 had revealed the boy’s cause of death to be “airgun projectile wound to abdomen”.
Giving evidence, Detective Sergeant Julian Gibbs, of Humberside Police, said that the force were called to the scene of the incident after receiving a call from the ambulance service.
He said: “Upon examination by family members, Stanley Metcalf was found to have a small hole to the side of the abdomen.”
Shortly after his death, the force said early indications pointed to it being a “tragic accident involving a pellet gun”.
Det Sgt Gibbs revealed that an investigation into the circumstances of the incident is ongoing and is still “at the early stages”.
Adjourning the inquest for a date to be set, Professor Marks described the Stanley’s passing as “sad and tragic”.