I dug my old M1 out of the safe today....she hasn't seen the light of day for a while.  She's a 50's era model, all SA, reimported from somewhere as indicated by the ARI Ord stamp on the end of the barrel.

The exposed metal on the rifle appears to have been "painted" with a durable brown substance.  It does not come off during cleaning and I never really paid attention to it before but now I'm curious.  

Anyone know what it is?

nothing?

I had some of the same on one I received.  Near as I could figure it was just dried linseed oil or cosmoline.  Pretty tough to get off.  Fingernail polish remover worked on it.  Hope this helps

thanks for the tip.....you were spot-on.  Sat down with some of the wife's polish remover and it's doing the trick.