Here's a tip for quick and easy de-cosmolining of a Yugo.
Find a baby tub or something similar capable of holding the rifle action.
Boil a lot of water.
Detail-strip the rifle and set the stock aside.
Dump all the metal parts in the tub.
Pour the boiling water over all the metal parts, until they are submerged in hot water.
The cosmoline will melt off and float to the surface, where it will collect on the edges of the tub. Do not use an indispensable container...the tub will be ruined afterwards, as the ring of cosmoline will be hard to remove.
Keep parts submerged for a few minutes. Scrubbing with a nylon bristle brush made for dish cleaning will speed up the cosmo removal.
Remove the parts from the hot water, and let them dry in the sun for an hour or two.
Spray the metal parts down with Powder Blast...it will get all the remaining cosmoline off the rifle in a hurry.
Wipe down the rifle and lightly lubricate all metal surfaces, as the Powder Blast will have taken all the oil and lube out of the metal, and it will rust very quickly if it is not oiled.
I cleaned my Yugo in about three hours that way, and half the time I spent waiting for the metal to dry in the sun after the trip to the hot tub.