[RetiredTexasVet]

“...he removed the pistol’s magazine and put a bullet in the chamber before then mistakenly reloading the gun...”

My guess is that he cocked the gun, which chambered a round, and then removed the magazine. He then put another magazine in and assumed there was no round chambered. A common, but fatal, mistake.

[COBOL2Java]

My guess is that he cocked the gun, which chambered a round, and then removed the magazine. He then put another magazine in and assumed there was no round chambered. A common, but fatal, mistake.

Sad, but too often true. Negligent discharge

[TexasGator]

“My guess is that he cocked the gun, which chambered a round, and then removed the magazine”

Cooking a pistol does not chamber a round.