Open revolver cylinder at the suicide death scene

Revolvers with an open cylinder were found at three death scenes of apparently self-inflicted gunshot wounds. All three handguns were Smith & Wesson.38 or.357 revolvers. Investigation revealed that firing the gun with the thumb on the cylinder release latch could disengage the cylinder. A combination of gravity and recoil impact against the thumb would open the cylinder and even allow the casing and the unspent cartridges to fall from the gun, creating a confusing death scene.