What should the gunner ensure about the cross-leveling locking knob before firing?

The correct answer highlights the importance of ensuring that the cross-leveling locking knob is hand-tight before firing. This adjustment is crucial for stabilizing the mortar and ensuring it is level when in position. If the cross-leveling knob is not tight, it can lead to inaccurate firing angles, potentially causing the round to miss its intended target or lead to a malfunction of the mortar system during firing.

Having the knob hand-tight ensures that the cross-leveling mechanism is secure enough to maintain the needed alignment but still allows for fine adjustments as necessary. Tightening it to this degree balances security and flexibility. Proper handling of this adjustment directly impacts the mortar’s performance and the safety of its operation, making it a critical step in the preparation process before firing.