The young female recruit, 18, died from a gunshot wound to the head at the Surrey base in November 1995 - one of four recruits who died there over seven years.
Delivering his conclusion following a three-month inquest into her death, Coroner Brian Barker QC said: “The conclusion is self infliction.”
He added: “This was an intentional discharge by Ms James.”
The coroner said Pte James had a “preoccupation with death” and would sometimes talk to her friends about what guests she would want at her funeral.
He said she was “disillusioned” with the Army and had a troubled adolescence which included an overdose.
She had light-heartedly talked to friends about how “easy” it would be to shoot oneself at the Army barracks.
Mr Barker said: “There can be no reasonable doubt that Ms James carried out an intended action and knew that its consequence would be death.
“I’m satisfied so that I’m sure Ms James inflicted the fatal shot and intended to die.”