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View Full Version : When the Cosmoline Isn't Properly Removed


Kerplow
02-08-2012, 2:26 PM
So when I took apart my Finn nagant I noticed that the bolt had what looked like cooked grease in many of the cracks and crevices, It wouldn't come off easily with solvent, but brake cleaner made it wipe off pretty easily.

Underneath the stock, the rest of the gun seemed to also be covered in ancient, smoothed over cosmoline. What I noticed was that in the high finger traffic areas like the receiver and magazine, but underneath the stock, the places that seemed to have leftover cosmoline also had light rust underneath it. You might think cosmoline is so snotty that whatever it's on just ain't gonna rust, but that does not appear to be the case. I'm guessing that when the cosmoline heats up and moves, it picks up moisture and debris that end up stuck in or under the cosmoline, allowing the metal to oxidize.

So the moral of the story is: When you get a sweet new C&R that's still smothered in delicious arsenal cosmo, make sure you thoroughly clean it off the entire gun, just because it looks to be covered in grease does not mean the grease is still doing it's job. :thumbsup:

TheExpertish
02-08-2012, 9:55 PM
You sure it's rust? I've noticed alot of time that the "rust" was just orange colored cosmo.

Flyin Brian
02-08-2012, 10:08 PM
So when I took apart my Finn nagant I noticed that the bolt had what looked like cooked grease in many of the cracks and crevices, It wouldn't come off easily with solvent, but brake cleaner made it wipe off pretty easily.

Underneath the stock, the rest of the gun seemed to also be covered in ancient, smoothed over cosmoline. What I noticed was that in the high finger traffic areas like the receiver and magazine, but underneath the stock, the places that seemed to have leftover cosmoline also had light rust underneath it. You might think cosmoline is so snotty that whatever it's on just ain't gonna rust, but that does not appear to be the case. I'm guessing that when the cosmoline heats up and moves, it picks up moisture and debris that end up stuck in or under the cosmoline, allowing the metal to oxidize.

So the moral of the story is: When you get a sweet new C&R that's still smothered in delicious arsenal cosmo, make sure you thoroughly clean it off the entire gun, just because it looks to be covered in grease does not mean it's the grease is still doing it's job. :thumbsup:

I've never heard anyone theorize that cosmoline causes corrosion.

I don't suppose you considered there was probably corrosion on the metal when they applied the cosmo?

Kerplow
02-09-2012, 12:11 AM
You sure it's rust? I've noticed alot of time that the "rust" was just orange colored cosmo.

yeah, definitely rust. The blue is gone in the places where the rust was forming.


I've never heard anyone theorize that cosmoline causes corrosion.

I don't suppose you considered there was probably corrosion on the metal when they applied the cosmo?

I'm not theorizing that cosmo itself causes rust, but rather, that cosmoline can entrap moisture or other undesirables which may cause rust.

sure, there could have been rust before the cosmo, but you can also see where there are old rust pits that were blued over. I suppose it's always a possibility that the finns got lazy with their metal prep and blued right over some active rust.