A firearm with all of the typical 1911 safeties
A Glock's safe-action trigger, or similar mechanism
A firearm with one manual safety
Muscle memory from sufficient training, no thinking required
A firearm with a Bio-safety (DNA analysis, fingerprint recognition, etc.)
No safety is needed, guns and shooters are flawless without
No gun is safe, except for the one in the scrap pile
The most important safety device resides in your head, between your ears.