Assorted SKS information.
I ended up stripping the cosmoline off a surplus Yugo SKS for a friend. It turns out that either Goo Gone or Ballistol does a decent job of removing cosmoline.
After I finished, I tried the trigger and it was really bad. Long, gritty and heavy. I figured it couldn't really be that bad, so I stripped the trigger, cleaned, lubricated and reassembled it.
I learned a couple of things. First of all, to remove the hammer, use a short length of pipe with an inside diameter that's about the same size as the hammer. Slip it over the hammer and use it as leverage to pull the entire hammer back until the hammer lugs clear the trigger group "housing". You can do it without the pipe, but it requires significant effort.
If you don't have to remove the trigger/trigger bar itself, avoid doing so. If you have to remove it, make a slave pin with one rounded/tapered end to get the hole lined up for reassembly. Otherwise it requires at least 3 hands to hold everything in place and drive the pin in.
The biggest change came from cleaning and lubricating the "rails" on the sear and trigger group housing. With the grit removed and some decent lubricant in place, the trigger was actually quite good. Still long, but lighter and very smooth. Almost like a good DAO pistol trigger. That cleaning/lubrication can be accomplished by removing the magazine latch. Drive the forward pin (the one that protrudes on both sides of the trigger group housing out from left to right. The magazine latch and the magazine latch spring will slide out the front of the trigger group housing and you can then remove the sear out the front as well.
Clean the parts, and the rails inside the trigger group that accomodate the sear and magazine latch and then put it all back together.
The front of the trigger bar and the lower front of the sear don't need to be lubricated. They need to engage each other without slipping. If the sear or trigger bar is worn, lubrication can cause the trigger bar to slip off the sear and the hammer won't drop.
If that happens, it's probably time for the attentions of a gunsmith unless you are particularly handy with a file, have a light touch and understand how the two parts are supposed to interact.
When you're cleaning the disassembled gun, you'll eventually get irritated by the disassembly pin which flops around and generally gets in the way. To prevent this, get a plastic drinking straw and cut off a length that's just long enough to fit on the shaft when the pin is pulled all the way out. Split the straw length and slip it over the shaft. It will hold the disassembly pin fairly securely and will hold it out of the gun where it won't interfere with a cleaning rod and won't flop around.
To strip or reassemble the recoil spring assembly, use a thin rod (the cleaning rod will work) run up the back of the recoil spring guide to prevent the two-piece recoil spring guide from collapsing/telescoping into itself. Pull back on the spring and slide the spring retainer off the guide.
When you're cleaning a Yugo, after you've removed the gas tube & piston, move the gas "button" to the single shot position, flip the grenade launcher sight up and then move the gas button to the forward position in the slot and remove it and the spring that tensions it. Next pull the gas block insert out of the gas block and fill the gas block cavity with a couple of cotton balls packed into place. That will keep solvent from running out of the gas hole during the cleaning process. You can remove the cotton with long nose pliers when you're done.
If the gun is a standard SKS without the single shot option, skip all the grenade launcher stuff and just poke some cotton inside the gas block.
I thought it was interesting to find RC hardness test marks throughout the gun.
The cleaning kit needs to go into the buttstock cap first.