SKS cosmoline removal (Please help)

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Jul 6, 2012
I just bought my first SKS, a Yugo M59/66 and when I stripped it down there was still cosmoline in the trigger assembly and on the internal parts of the frame. I have the trigger assembly soaking in warm water and Simple Green right now.

Is it okay to soak it overnight in the water+Simple Green?

I used a hair dryer and huge air compressor to blow out all the cosmo from the nooks and crannies. It melts right off with the hair dryer/air. But I just want to know about soaking some of the parts.

I know brake cleaner works but I wanted to try something less harsh first. Please post in ANY info you have. Thanks THR.

I'll start by saying I have NO sks exp, and have not tried Simple Green for Cosmo but love it for a general cleaning product and have heard alot of good things about it. I just cleaned my first Mosin Nagant 1942 Tula 91/30. For the bolt and other detachable metal parts I swished them in mineral spirits, scrubbed what I could with an old tooth brush, wiped with a paper shop towel (the tough ones in the box), then sprayed and wiped down with wd-40. Good luck and hope the simple green 'cuts it' for you. It would probably be ok to leave over night but I personally doubt I'd chance it, then again I'm overly cautious.
I bought a Mosin last week and the Simple Green worked like a charm, I recommend it 100%. The cosmo came off easy with the SG and I soaked the bolt and trigger in it as well. Give it a try, you won't be disappointed. I will leave it in overnight, it can't rust that quickly. Thanks for the reply.
I would avoid Simple Green, or any detergents in a water solution.

You could use Ed's Red or a variant of Ed's Red - a mix with more kerosene, that is volatile enough to disolve the Cosmoline, but it's less harsh than Brake Cleaner.

If you do resort to Brake Cleaner/Carb Cleaner/Engine Degreaser - make sure you purchase the stuff that says "Chlorine Free"
I just took the trigger assembly out of the soak and sprayed it down with WD-40 and then blew it dry with an air compressor. What a difference without all that cosmoline. I will soak the stock in the sun tomorrow after work (can't soak it all day around here in MA, neighbors will call the police).

Thanks all.
Anything small enough to fit in a boiling pot of water here. Make sure u use a pot u can throw away. dry the parts and oil.
Brake cleaner is just fine. I wouldn't hose down the entire gun, get all of the cosmoline off, hose it down some more and then just let it sit; without oil, but as long as you oil it reasonably quickly after you de-cosmoline it, it should be fine.

It isn't that the brake cleaner is corrosive, it is that it is drying out the metal, and then leaving it unprotected.

Boiling is my tool of choice, then I can hose out the pot with brake clean... The only part that I can't usually boil is the barrel/receiver.
Breakfree CLP cuts cosmoline just fine, and will let you avoid dealing with nasty stuff that may harm your skin or the wood. Squirt or spray it on, then wipe it off.
I haven't seen it mentioned yet, but, make sure to disassemble your bolt/firing pin to clean it exceptionally well.

Cosmoline can get built up in the bolt, causing the firing pin to protude enough to give you uncontrolled slam fires.

There should be instructions on the web somewhere for it, if not, let me know and I will scan my disassembly book for you. You will need a small punch and hammer to get the bolt apart IIRC.

Cheap old Rubbing Alcohol works great for cutting the grease and won't damage the finish on any gun I've ever used it on. Let is soak awhile then either air dry or use compressed air. Break Free CLP also works great but is considerably more expensive than a large bottle of alcohol.
Mineral spirits (paint thiner), large plastic tub and various size paint brushes and toothbrush work great.
Why do you recommend the non chlorinated variety of brake clean? I worked for a promod drag racing team back in my college days and we cleaned absolutely everything with brake clean (the regular stuff), as my crew chief swore the non-clor stuff was not as good.
Chlorinated stuff is a bit worse for your health. Not going to kill you tomorrow but not helping either. I've used both for cosmoline removal and had great results no harm to the finish just re-oil when your done.

I've done a few Yugoslavian Mauser and I don't like stripping the bolts. To get them totally clean I've boiled them and I've baked them (very low heat), I've found I prefer to boil them.

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Go to lowes and get a can of kerosene and a large shallow tub for the metal. Kerosene takes off cosmoline easily and is pretty cheap. The wood is more of a problem, I used an oven and it took forever. If I were doing it now I'd put the stock in a black garbage bag or two with some cat sand and put it in the hottest, sunniest place you can find for about a week. But I did want all the cosmoline gone, if some weeping out occasionally doesnt bother you, you shouldnt need as long.
I prefer using mineral spirits and/or paint thinner on all the metal parts to strip the cosmo. Its cheap and effective. Pour the spirits into a paint tray, soak the tiny parts. Pour spirits onto the larger parts and grab a nylon brush and start cleaning. Let all the parts try and coat them all with a light coat of gun oil to prevent rust.

Baking wood stocks in the heat is my preferred method of leeching out cosmo. Its a slow process, but it gets the job done.
I am afraid to mention a substance I use regularly for cleaning cosmoline because the "safety" folks go ballistic. Hint: It is a very common liquid and you probably have a tank full of it in the garage. It is usually sold by the gallon and, while the price has gone up, it is still a lot cheaper than other cleaners recommended here. But don't light up a cigarette while using it or you might find out about the evils of smoking in a very direct way.

I will agree with the kerosene or mineral spirits. When I got my sks home I used lots of mineral spirits, an old toot brush, q-tips, and LOTS OF ELBOW GREASE. I think it took me about 2 good hours to clean the cosmoline off the metal. I soaked the trigger and bolt in a small bin filled with kerosene/degreaser overnight to make sure it was all good. I don't think you will have any problem with the simple green doing the same thing. I also made sure to oil EVERYTHING the next day. The stock I just wiped down with a mineral spirits soaked rag and let the rest of the cosmoline weep out over time.
I have been cleaning cosmolene off guns for ~15 years.
Every approach has advantages and disadvantages.
Now I wipe off everything with paper towels to get the big stuff off.
Then I take a hot shower with the major gun parts, while scrubbing the parts with a tooth brush. [the first part of bonding with your baby is giving it a bath]
I like to get the parts in really hot water, and then wipe them off fast, so the rest of the water will evaporate off the hot parts.
Sometimes I use Simple green.
Sometimes I use a hair dryer.
If simple green gets on steel, then I rinse, dry, and apply oil.
Steel parts can get so clean from simple green that they quickly rust.

On Yugo SKS rifles... I bought a couple cases of them from AIM or Century at $70/each. Looks like I only kept 3 and sold the rest at $130. That was ~ 10 years ago. Prices have gone up since then. They are the Cadillac of SKSs in how they are made, but not good accuracy for me. I have done the drill and tap for scope, the single shot no gas, the glass bed, the trigger job, the stock butt extender, the careful handloads, and the grenade launcher removal. The Albanians are junk. Have not shot my Russian. But some Chinese SKSs really shoot well for me.
Thanks everyone. I got most of it out with compressed air and WD40. Mineral spirits did help as well.

The stock is still embedded with it so I will wait for a hot day or use my heat gun to get the Cosmo out. Thanks!
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