Is your new rifle a Chinese SKS from Cabela's ?
I played the online lottery too and got a decent little rifle, much better condition than I expected and that I have ever seen in store. To my surprise mine personally was not very coated in preservative oil. I wouldn't have called it Cosmoline, more like heavy oil/grease. I was able to clean everything easily with WD-40, Remington Action cleaner and G96 and some rags.... oh and some dishsoap for the wood.
This is not my typical cosmoline routine, I usually use mineral spirits to remove the cosmo, rinse with water and dry with the air compressor. Then dry with an air compressor and heavily oil with good stuff, wipe and reassemble. Stocks heated with Hot water and soap to remove grease and if wanted to strip the stock use Tilex (non bleach) and natural stain remover. The stock is thoroughly washed after all stain/grease is removed with soap and water to deactivate any of the chemicals. Then the rifle is hung in warm weather and placed in from of a dehumidifier if cold out. It is very important when soaking a stock that it is dried out evenly and that it is aligned strait with no pressure on the stock or it may warp or bend is it dries slowly or unevenly. Then when the stock is clear and dried may use a new stain, light steel wool buff and true oil or linseed oil. I used this method on many Eastern bloc arms. This process usually takes 3 to 5 days depending how many coats of stain/true oil/linseed applied.
The Chinese SKS was much easier to clean, it just had that heavy Chinese oil on it not the waxy sludge paste that is true Cosmoline. I was able to break the rifle down and first wiped down the wood stock and top guard with soapy water to remove the oil on the stock. Then I let it dry, this is all I did with the stock as it cleaned up nice and the original stain/coating was fairly acceptable (like a rifle that has been around a bit but cared for). The metal was surprisingly not rusty anywhere, I was able to spray it with WD-40 and Remington action cleaner then wiped with some rags (old underwear). This worked surprisingly well on this less offensive oil. Following the nasty preservative oil removal I simply sprayed the metal with G96 liberally and let sit for a few hours. Then I wiped down the metal and reassembled the rifle, looks like it will work flawlessly now. Overall tool me about 2 hours. Importantly I did hammer out the pin in the bolt to free up the firing pin to ensure the bolt and all of its parts were perfectly clear of grease and when reassembled was totally moveable tapping it with your fingers. This is one of the most important steps to ensure you clear your firing pin on every SKS you buy. Also with each service check/cleaning make sure the firing pin is free floating and not sticking as a stuck firing pin risks slam firing.
For a Stuck stock and any disagreeable milsurp parts I threaten them and use the Rubber Mallot as much as possible. If you can't get your magazine out after removing the trigger group you can use a brass punch or old brass shell to tap out the magazine with the shell as a tap and mallot tapping it out. For the stock I flip the rifle over on my rest (upside down) and tap the bottom of the back of the receiver with the same shell to loosen it a bit then flip the stock over (right side up) and lift the barreled receiver out moving it forward away from the front of the stock.
For Barrels Coated in Cosmoline, one option is to buy a 3" or larger PVC pip and cut it to approx 3-4 feets long and place an end cap on one end. Then fill the pipe with Mineral Spirits and dunk you barrel in the pipe. Another option is to use a long tray like used with wallpaper and just submerge the whole thing. Sometimes sellers use black paint on milsurps, if you see tons of black stuff coming off and find bare metal under that pain you may have to re-blue your firearm. Don't fear this as cold blue works awesome (in the summer) You degrease the metal perfectly like you already have done with mineral spirits or Acetone and apply the liquid blue. After applying the blueing you wait about 10minutes and dunk each metal part in water and then buff with steel wool. Then you repeat this process several times (about 4-8 most times) to see the metal develop a rich blue and when done oil it up and reassemble.
PM if you have any questions
