Battle Creek Police Detective Lt. Austin Simons said Nicholas Ullrich, 34, died about 10 p.m. Wednesday from a single gunshot wound to the head.
Simons Ullrich was found at a home where he and resident Samuel Castanier, also 34, were celebrating the birthday of a third man. Simons said the men were drinking and playing with a revolver loaded with a single cartridge.
Simons said the men believed they were safe by looking at the cylinder before pulling the trigger, but forgot the loaded chamber advances when the trigger is pulled.
Castanier remains in custody, facing open murder charges.