Someone came by searching for “accidental gun deaths vs self defense.”
For 2010, the last year official data on fatal firearms accidents are available, the total was 606.
For 2010, analysis of CDC and FBI data finds there were at least 1400 and no more than 1700 justifiable homicides. Analysis of media reports puts the number of gun related justifiable homicides during 2010 at between 1340 and 1640.
So self defense shootings are more than twice as common as fatal firearms accidents. If you subtract the estimated number of fatal hunting accidents; self defense shootings are about six times as common as fatal firearms accidents.