Here's a poll from another forum with almost 600 responses selecting options that applied to their unintentional discharge.
https://www.thehighroad.org/index.php?threads/how-did-your-unintentional-discharge-happen.114287/
Only about 12% occur as the result of the trigger snagging on something, the gun being dropped. or parts breaking in the gun. We tend to worry a lot about these kinds of incidents, but even when you roll them all together into one category, the still account for a relatively small percentage of the overall picture.
Another 14% or so are the result of the trigger doubling (the gun firing a second time unintentionally immediately after the gun was fired intentionally) which is usually not a big problem since the gun was intentionally being fired it was presumably being pointed in a safe direction at the time.
A little over 50% happen when the shooter intentionally pulls the trigger.
Another 20% happen when the shooter unintentionally pulls the trigger.
The last three categories all involve the shooter's finger being on the trigger. Which means that if you don't want the gun to go off, keep your finger out of the trigger guard-that eliminates about 85% of unintentional discharges.
Dry firing is a good practice technique and can be done safely, but it's important to understand that it's breaking the first rule of how to avoid unintentional discharges---keep your finger off the trigger.
That means that it's extremely important to implement other safety protocols and stick to them religiously when dryfiring.
1. When dryfiring, ALWAYS fully check the gun to make sure it is unloaded before starting.
*EVERY time you put it down, check it fully again when you pick it up.
*EVERY time you resume dryfiring after any kind of a break, check it fully again when you start up again even if you didn't put the gun down.
*If you are distracted or interrupted, check it fully again when you get back to dryfiring even if you didn't put the gun down.
*Always check the chamber(s) both visually and manually. If it's a revolver, be sure to check EVERY chamber carefully.
2. When dryfiring, always use a backstop of some kind. A bookcase full of books, a heavy piece of furniture, a brick wall, etc. Something that will stop the bullet if something goes wrong.
3. When dryfiring, NEVER point the gun at yourself, another person, any animal or any valuable property. If there IS an unintentional discharge it doesn't have to be a tragedy.
4. When dryfiring, NEVER have live ammunition within reach. If it's a gun that is normally loaded, unload it in another room and dryfire in a room with no ammunition in it.
5. Dryfiring requires the same unloading & safety procedure every time. If you're going to dryfire 100 times, go through the entire procedure. If you're just going to dryfire 1 time, go through the entire procedure. If you're going to do 2 sessions with a short break in between, go through the entire procedure at the beginning and then again after the short break.
6. Don't dryfire if you are tired, distracted, impaired or can't devote your full attention to the process.