That can't be true, for the number of fatal gun "accidents" per year is ~600 (scare quotes because some number of those are whitewashed murders or negligent homicides), the number of non-suicide homicides is ~11,000, and the number of suicides using a gun ~19,000.
It's very easy to see that the number of self-defense incidents using a gun is substantially larger than those numbers, from anecdotes, to the very lowest formal estimate of 108,000 (see the CDC funded 2013 monograph at http://www.nap.edu/catalog/18319/priorities-for-research-to-... pages 15-6). The highest estimates range to 2.5 million, but that was a while ago, and crime rates have continued to decrease.