If I remember correctly;
Disabling a 105mm howitzer.
If very short of time, the firing mechanism was removed from the breech block.
If short of time the breech block was removed as well.
Time permitting, a maximum propellant charge, all 7 bags and a projectile was loaded, and a projectile was inserted in the muzzle with the fuse pointed at the breech. I think the fuse setting was super quick.
The air and hydraulic recoil systems were opened and drained.
The 2 optical sights were smashed
The howitzer was then fired, and if the preceding was done properly, was now useless.