Again I will happily accept any data which shows the statistical insignificance of non-intentional negligent gun deaths or at least that they are being properly prosecuted.
Data:
From the CDC, 2017 unintentional deaths by firearms (no indication whether it was negligent), all age groups: 486
From the same data:
64,000 deaths due to poisoning
36,000 deaths due to falls
2900 deaths due to fire
970 pedestrian deaths
Negligent firearms deaths fall between "machinery" (at 572) and "cyclist" (at 345). For context, I would suggest that the state of current mandatory gun safety regulations probably falls between machinery (generally well-regulated by OSHA and other governmental agencies), and cycling (generally unregulated other than general helmet-law and rules-of-the-road regulations).
If you're curious, the same trend holds up during the 2000 to 2017 sample period. Negligent firearms deaths falls between machinery and cyclist deaths, with motor vehicle, poisoning, and falls representing the top three causes of unintentional deaths.
With 3142 counties in the US, that's approximately 0.15 annual deaths per county (or 1 negligent firearms death per 6.46 counties) between 2000 and 2017.
Brief Commentary:
I am not a statistician.
You may access the data above and determine whether negligent firearms deaths would be considered "statistically insignificant" for this sample period. Given that they appear on the CDC's top-20 causes of negligent deaths, I suspect they are not insignificant, but the number and incidence is quite low given the number of weapons in circulation in the US (generally reported as ~300 million) For comparison, the number of registered personal vehicles is around 270 million in the US.
If the overall intent is to reduce negligent deaths, I would suggest a greater focus on improving road and vehicular safety, as these account for 33.3% of all negligent deaths between 2000 and 2017 (including MV, land vehicle-other, pedestrian, and cyclist), while firearms-related deaths account for just 0.5%. Much more room for refinement there, and no clear-cut constitutional restrictions (other than 9th/10th amendment generalities). Looking to Europe, the requirements for a driver's license are much stiffer than they are in the US-- perhaps we should research adopting Europe's more stringent driver licensing laws.
Not interested in arguing for against private firearms ownership on SAF-- just responding to the request for statistics and providing some perspective from a layman.
EDIT NOTE- I initially linked directly to the data output, but it appears the link expired. I have updated the embedded link to point to the CDC's "Leading Causes of Deaths" database. "Negligent Firearms Deaths" are listed under "Unintentional Injury" in the output.