Final answer:
The question seems to be about a specific firearm action, but it does not align with the options provided. The concept of recoil in firearms is based on Newton's third law, where the action of the bullet moving forward causes an equal and opposite reaction, making the gun recoil. It's unsafe to stand behind a recoilless rifle due to the backward escape of gas and debris.
Step-by-step explanation:
The feature of the Bergmann falling locking block action referred to in the question could be the locking mechanism of firearms, but none of the options given directly relate to the Bergmann falling locking block action. Therefore, we cannot confidently select one of the choices provided. Instead, I will address the underlying application of physics in firearms.
When an ordinary rifle is fired, it recoils because of Newton's third law, which states that for every action, there is an equal and opposite reaction. As the bullet is propelled forward by the explosive force, the rifle is pushed backward with an equal force. In contrast, a recoilless rifle is designed with an open barrel at both ends, allowing for some of the explosive force to escape backward, which counteracts the recoil effect. However, it is not safe to stand behind a recoilless rifle when it is fired, as the escaping gas and possibly shell fragments can pose a danger.