bf2, Howdy;

Personal preference is to use a CPL (Cleaner Protector Lubricant), like Breakfree
(I'm just a customer), the military switched to it from WD-40 when they found WD
attracted moisture ... (not good for firearms). Fill up the lock with Breakfree and
allow it to sit for awhile (time dependent on amount of crud in the lock), dump into
an approved container. If you are concerned about the keying mechanism then I
would drip some rubbing alcohol into it to displace the CPL, allow it to dry them apply
the graphite.
For ongoing preventive maintenance I would suggest a light spray of CPL into the
locking mech. on a monthly basis, more often during less then good weather.

hank