Negligence, where the discharge of a firearm is concerned, in a building where people may assemble, and no one is injured is a criminal offense in Missouri (RSMo 571.030 - Unlawful use of weapon; 565.060 - Assault, Second degree). Prosecution is a different issue. Other states may consider a negligent discharge where a injury occurs not to be a criminal offense. The "instructor" should be permanently disbarred from any further training events, as a business, at a minimum.
No excuses, no second chances, Mr. Dunlap is lucky that Mr. Piemonte does not seem to have filed any charges for what is reported to be a minor injury.
Actual wording 571.030
Unlawful use of weapons--exceptions--penalties.
571.030. 1. A person commits the crime of unlawful use of weapons if he or she knowingly:
(1) Carries concealed upon or about his or her person a knife, a firearm, a blackjack or any other weapon readily capable of lethal use; or
(2) Sets a spring gun; or
(3) Discharges or shoots a firearm into a dwelling house, a railroad train, boat, aircraft, or motor vehicle as defined in section 302.010, or any building or structure used for the assembling of people; or
Check for updates
565.060. 1. A person commits the crime of assault in the second degree if he:
(1) Attempts to kill or knowingly causes or attempts to cause serious physical injury to another person under the influence of sudden passion arising out of adequate cause; or
(2) Attempts to cause or knowingly causes physical injury to another person by means of a deadly weapon or dangerous instrument; or
(3) Recklessly causes serious physical injury to another person; or
(4) While in an intoxicated condition or under the influence of controlled substances or drugs, operates a motor vehicle in this state and, when so operating, acts with criminal negligence to cause physical injury to any other person than himself; or
(5) Recklessly causes physical injury to another person by means of discharge of a firearm; or
Seems to me knowingly and recklessly comes into play here to be found in violation knowingly and recklessly would have to be proven