What and how I use to clean cosmoline out of mil surplus rifles.
I like using a tea kettle and hoppe's elite bore gel or number 9, lots of bore snaking, brushing, cussing, and a few beers to help the owner along.
I have found that a proper size copper bore brush on a mil surp cleaning rod chucked into a drill with hoppe's elite bore gel works great. For dark crud in the rifling, use kano kroil for 1 hr and flush some WD-40 to use its solvent carrier to clean like a solvent should.
Then brush the heck out of it. Then do it again. Then one final time, then bore snaking it a few times and inspect with a bright white light.
To execute the above:
several kettles of boiling water rifle assembled. then dissemble and repeat where necessary.
Next obtain Koril oil which is high in benzine thus cutting through suck on cosmoline and gunk. I then follow by hoppe's elite bore gel(Or number 9)This combination will help remove the crud like no body's business.
Kroil is a legendary penetrating oil for stuck bolts. good stuff to have around, Kano Koril.
Use several passes with patches soaked through with Kroil. Then give a good squirt or 2 more down the bore. Go enjoy the game(FIFA RULES), come back and scrub hoppe's elite bore gel(wall mart carries it) a brass brush you never wish to use again and chuck the rod in the drill and go nice and slow while cussing to find your still not there yet.
Drink some malted beverages of your favorite and continue using 3 bore snake passes to see what it looks like. Then drink a few more while you repeat. Once patches start to come out clean, then oil as your like.
For range cleaning using known or suspected corrosive ammo, Windex down the bore after firing, while still hot seems to remove gunk pretty well. The object is to dissolve and neutralize the corrosive salts.
If you use straight household ammonia be aware of not cleaning the ammonia out of the bore as it will cause nasty rust if mixed too strong for too long.
Ed's Red works like magic on everything, so that gets a nod as well.
For range cleaning Windex works great, and doesn't usually contain enough ammonia to accelerate rusting like the household strength does, but still should be followed by at least a vigorous bore snaking or WD-40(Or your choice water displacing substitute). It is still a possibility, so bear that in mind.
http://age-web.age.uiuc.edu/bee/RESEARCH/corrosion/nh3-1.htm
For the stocks, I have found that a trash bag with strategically placed coat hanger to keep the bag from contacting the stock placed out back on a hot summers day or two will get quite a bit. Hair driers/ heat guns help, but slowly and not full tilt heat for long periods of time. The trunk wrapped in old towel of a black car works great too, but your car will smell funny for a few days.
The tea kettle method for me is the best thing since sliced bread. Heat up a cup for your self, the rest goes to the mil surp in question. Bring it to a whistle, then pour down the barrel, on the barrel, put the bolt in the sink an face down and pour it for a bit, then flip face up and pour pour pour away(I brace Mosin bolts with coffee cups) and pour it all over leaving it pin down over paper towels to collect any stray grease.
I typically get 70-95% of the gunk out by following my methods on the first try. Your mileage may vary.
Sorry for being long-winded and on the off chance nonsensical, its late and I'm heading to bed.
Hope this helps you with your question to find safer methods. I deem most of these to be safe if Google is your friend you will find lots of suggestions to tackle this problem
.
-Bill
WD-40 does a good job on cosmoline. I will stand by the hot water and dish soap for the corrosive salts from firing. Be sure to rinse the cleaning rod and brush so the salt isn't transferred to another rifle or back to the one you just cleaned. WD-40 on the stock is no problem for wiping down the cosmoline.