I've read several articles over the years claiming that a certain (unknown) percentage of "accidental gun-cleaning deaths" are actually suicides, with the motive that most life insurance policies won't pay out to the family in the case of suicide, but they will for "accidental death". Someone intent on accomplishing that goal would simply get out their cleaning supplies and set them in front of themselves to make it appear to have been an "accident".
This person could have had a debilitating mental disorder (in which case he not to have had access to firearms), or been depressed, possibly due to having a serious (terminal) illness and wanted "a way out". Also could have simply been negligent.
I have to wonder if mentally competent terminally ill people had the option of legal euthanasia, and the insurance company would pay on the life insurance policy under those circumstances, if the number of "gun accident" deaths would decrease. It's such a small number of deaths to start with, the total data set might be too small to reach a reliable conclusion.