Check out the following link..I used the tips on a recently bought used shotgun, and guess what it wirks..!! in my case the onion was the start but eventually I had to go to the smooth steel wool with gun oil..watch the video and you will get what i am saying.

http://www.ehow.com/video_4791113_re...pots-guns.html

never heard of the onion or aluminum foil.
what a gunsmith once taught me...
a can of gunopil and 000 steel wool. needs to be 000 grade and only use a little piece of it at a time and do small sections, then toss and tear you off another small piece and start over.

I agree with the steel wool..That's eventually what I ended doing..

Originally Posted by jimmy

..!! in my case the onion was the start but eventually I had to go to the smooth steel wool with gun oil...

Originally Posted by zorro

hi , one of my revolvers developed a few rust specs , what is the best way to remove them without damaging the remaining blue ??
I know I am asking alot, many thanks zorro

I've always used a piece of balsa wood with gun oil on it, for this sort of thing.
Balsa is very mildly abrasive and won't remove blue or other finishes, or much disturb ancient patina.
If the balsa-and-oil treatment doesn't work, then try 4-0 steel wool (with oil).
(Sometimes, on a blued gun, steel wool dipped in cold blue will do the job pretty well too.)