Could Mortar Shells Serve as Grenades by Impact Detonation?

The concept of using mortar shells like grenades, particularly in situations where force is applied to their base, has intrigued many. This practice, often depicted in movies like Saving Private Ryan and Hacksaw Ridge, has led to questions about the feasibility of such a tactic. In this article, we explore the practicality and historical context behind this intriguing military technique.

Understanding the Mechanical Design of Mortar Shells

Specific models of mortar shells, particularly those used in World War II, were designed with a built-in mechanism to detonate upon impact. This mechanism is known as the percussion fuze. The fuze is positioned at the nose of the shell and is designed to initiate the explosion when the shell experiences sufficient force during impact.

However, for safety reasons, the firing mechanism is disabled during transportation. A safety pin, held in place by a spring-loaded mechanism, ensures the firing mechanism remains locked. This arrangement allows the shell to be transported safely without the risk of premature detonation.

Triggering the Detonation: The Process Explained

The trigger mechanism of the mortar shell involves a small bar with a hole drilled through it. This bar is kept under constant tension by another spring. The safety pin is inserted into this bar, preventing it from moving. When the mortar is fired, the acceleration experienced by the shell exceeds the tension of the spring holding the safety pin in place. Consequently, the safety pin is released, allowing the firing mechanism to activate and set off the explosion.

This explains why, in movies, soldiers would "jolt" the mortar shells by dropping them on a hard surface. This action simulates the force of being fired, thus triggering the same mechanism that would trigger upon impact.

Historical Context and Practicality

In reality, the technique of using mortar shells as grenades by applying force to their base was indeed possible. This method was used in World War II, where 60mm mortar rounds were the standard equipment for many infantry units. The process involved removing the safety pin and slapping the tail of the mortar round against a solid surface to simulate the force of the launch.

However, there were several practical considerations:

Weight: Most mortars, especially those used in earlier conflicts, were incredibly heavy. In the context of grenades, which are typically small and lightweight, the sheer weight of a mortar shell would make it impractical to throw even for a trained soldier.

Explosive Radius: Mortar shells were typically designed to explode at a distance, meaning their lethal radius extended beyond the range a soldier could throw the shell.

Reliability: For a mortar shell to be effective as a grenade, it would need to be thrown to land on its nose, ensuring the impact fuze is engaged. This is more challenging in practice than in the controlled conditions of a movie set.

Conclusion: A Mix of Fact and Fiction

While the concept of using mortar shells as grenades is theoretically possible and was used in certain historical scenarios, it is largely portrayed through the lens of "movie magic" rather than practical battlefield tactics. The design of mortars and grenades serves different functions, and the weight and size of mortar shells make them a far less effective choice for a handheld explosive device compared to the traditional grenade.

The practice, while occasionally used, is not a widespread or reliable tactic, and the depiction in media is more a blend of historical accuracy and narrative convenience.