Before firing, the mortar crews should complete the following actions:

1. Inspect the three units of the mortar for cleanliness.

2. Clean the bore and firing pin with a clean, dry cloth. Do not apply oil to these parts before firing.

3. Do not leave any waste on the firing pin or in the barrel. Do not use grease.

4. Clean thoroughly and oil lightly all metal moving parts with preservative lubricating oil.

Cleaning After Firing

Clean the bore and all working parts of the mortar immediately after you complete firing. When cleaning cannot be accomplished immediately, apply oil to prevent corrosion. At the first opportunity, clean, oil, and inspect the mortar. If necessary, have repairs and replacements made by the unit armorer.

Clean the bore with rifle-bore cleaner immediately after you complete firing and 3 consecutive days thereafter (a minimum of four cleanings). The barrel should be cool enough to touch with your bare hand before using bore cleaner on it. The cleaner evaporates at 150F, and such evaporation causes dark spots on the barrel. When rifle-bore cleaner is not available, use a hot soapy solution or plain hot water. Clean the vent and firing pin, as described previously, using a liberal quantity of soapy solution instead of rifle-bore cleaner. Dry the parts by using clean rags and applying preservative lubricating oil. When cleaning the mount, take care to remove dirt from all crevices. Clean all moving parts with rifle-bore cleaner, dry them, and apply preservative lubricating oil to all surfaces. To distribute the oil over the working surfaces, operate the traversing and elevating cranks. Clean the socket on the baseplate, as discussed previously.