every couple years I clean my AK's.
The only exception is my SBR krinkovs.
I clean them every range trip.
One thing to make sure you do is remove the muzzle device and wipe down under it.
On the Krinkov's and Bulgy AK74's, the flashhider collects alot of moisture and you really need to make sure no rust will build up there.
I took the 4 peice off of my Saiga Krink and notice a fine red rust starting to form.
I dispatched it with a few wipes of a oily rag.
The only time you MUST clean a AK is when you had it out in the rain.
I knew this guy that NEVER cleaned his AK.
He took it to the range, blasted drum after drum out of it.
He came back home tossed it in his garage.
A couple month later he went back to the range.
The bolt/bolt carrier was rusted to the rails/trunion.
You could not budge it.
He hit the bolt handle on the edge of a concrete table. After a couple of hits, the parts came free.
Hit sprayed the inside with WD40 (via bolt hole in receiver), worked the action some, and blasted more rounds out of it.
This is the Standard procedure this guy uses for this rifle.
Every couple of range trips (with months between), his rifle would be frozen up and he would redo his WD40 spray.
To this day, and ten thousand rounds later, he has never taken the cover off the receiver nor has he put a brush down the bore.