Are there handguns small enough to fit inside a Petri dish? Or do you just aim the handgun at the Petri dish? Does the handgun need to be loaded? If it must be loaded, will blanks suffice? Does a larger caliber reduce the time needed to aim the handgun at the Petri dish? Is there a specific distance to the dish from which one must aim the handgun? Are rifles, shotguns, and machine guns specifically excluded? Will a sword work? It’s generally made of the same kind of material as a handgun. Is it necessary to stand on a chair while wearing a lab coat while aiming the handgun? Can two hands be used to aim the handgun? Does engaging the handgun’s safety have any effect on the contents of the Petri dish?
I don't know of any handguns small enough to fit into a petri dish. The handgun must be loaded and fired at the petri dish. A large caliber will be easier to aim since it would decrease the need for accuracy. Close range is a better distance. Shotguns and machine guns would do an even better job, rifles are fine. A sword decreases the likelihood of destroying a virus because of its low energy. Standing on a chair while wearing a lab coat makes you look cooler. Two hands can be used to aim the gun if it helps you. The handgun will not fire with the safety on, thus decreasing the probability of destroying the virus.