Which weapon is NOT authorized for use as a warning shot?

The MP5 is not authorized for use as a warning shot primarily because it is a submachine gun designed for close-quarters combat and delivers a higher risk of lethal force compared to other weapons. Warning shots are intended to deter without causing harm, and the use of a weapon that is capable of causing significant injury or death is not aligned with the principles governing the use of warning shots.

In general, warning shots should be fired using weapons and ammunition that minimize risk to life and property, focusing on establishing presence and deterrence rather than inflicting harm. This is why the other options—M4, M60, and M240—may be considered for that purpose under certain conditions where they can be fired in a controlled manner, such as using blank ammunition or firing to the side to minimize risk. The MP5's capabilities and intent as a tactical weapon do not support such nuanced use.