If it is unintentional, it is negligence.
Unintentional, accidental and negligent are all words that have established definitions which means that there should be no need to rehash this over and over. These threads should be focused on learning lessons from the situation, not on bickering over the meaning of words whose meaning isn't in question.
'Unintentional' and 'negligent' are NOT synonymous. They do NOT mean the same thing. They are NOT interchangeable.
For those who refuse to use dictionaries or look definitions up online, here's an explanation of the meanings of 'unintentional' and 'negligent'.
Unintentional just means that something happened even though it wasn't intended to happen. It is the opposite of intentional. It carries no negative connotation.
Negligent means that ordinary/proper care was not taken in the course of some activity. It has nothing to do with intent or lack of intent. It carries a connotation of guilt, culpability and liability.
Negligence is ONLY about whether or not proper care was taken. Negligence can occur during intentional AND unintentional actions.
Discharges can be intentional or unintentional. They can be negligent or non-negligent. One can tell the difference by using the established definitions for the terms 'negligent' and 'unintentional' and comparing those definitions to the circumstances of the discharge.
Examples
Intentional and not negligent.
A person fires a gun at a target with a proper backstop. The person intentionally fires the gun. Since proper care is taken to insure that the bullets are stopped safely without endangering anyone, there is no negligence.
Intentional and negligent.
A person fires a gun at a paper target which is set up in such a manner that bullets passing through the target will travel towards a populated area only a very short distance away. The person intentionally fires the gun. There is negligence because proper care is not taken to insure that bullets will not endanger others.
Unintentional and not negligent.
A person chambers a round in a semi-automatic rifle which is not known to have any safety or function issues. The person is using the proper ammunition. The rifle slamfires during the process. The person is pointing the firearm at a safe backstop during the process and therefore the bullet goes in a safe direction. The gun fires unintentionally. There is no negligence because proper care is taken to insure that the discharge does not endanger anyone.
Unintentional and not negligent.
A person fires a round from a semi-automatic firearm and the sear fails unexpectedly resulting in additional rounds firing. The additional rounds are fired unintentionally but because the sear failure was unexpected and could not reasonably be foreseen, there is no negligence.
Unintentional and negligent.
A person is carrying a loaded firearm with their finger on the trigger. They trip and as they fall, their fingers reflexively tighten on the gun, firing it. The person fires the gun unintentionally. There is negligence because proper care demands that a person does not carry a loaded firearm with their finger on the trigger.
Unintentional and negligent.
A person pulls the trigger of a loaded firearm without intent to fire the gun but without properly checking to determine that the gun was unloaded. That would be unintentional because the operator did not intend to fire the gun. It would also be negligent because ordinary/proper care demands that the gun be properly checked before dryfiring.
Unintentional -- possibly negligent or not negligent depending on circumstances.
A part (or parts) in the gun fail and the gun discharges as a result. That would certainly be unintentional. It wouldn't be negligent unless ordinary care would have discovered the parts failure before it caused the discharge. If ordinary/proper care couldn't reasonably be expected to discover the parts failure prior to the unintentional discharge then the discharge would be unintentional and non-negligent. If ordinary/proper care SHOULD have discovered the parts failure prior to the unintentional discharge then the discharge would be unintentional and negligent.
Unintentional -- possibly negligent or not negligent depending on circumstances.
A person holsters the firearm in a holster which has failed in such a manner that part of the holster can operate the trigger during the holstering process--and the gun fires during holstering. That is unintentional because the person had no intent to fire the gun. If ordinary/proper care would have noted the holster failure prior to reholstering then it would be negligent as well as unintentional. If ordinary/proper care couldn't be expected to note the holster failure then it would still be unintentional but it would not be negligent.