If you pass a background check and are able to obtain a permit for OC/CC, you're not going to "accidentally" shot someone. The 99.999% that own firearms legally aren't going to settle disputes by shooting someone. Or maybe you're talking about accidental discharge, and in that case that just wouldn't happen. A hammerless pistol on safety in its proper holster has virtually no way of firing. 

And no, anyone under the legal age to own a firearm should not have one. 

And how do you suggest we make obtaining guns harder? Mass shooters have been known to be mentally "stable" enough to appear eligible to obtain guns legally (We are talking about mass shooters here, not anything gang related or suicide cases).