on some older colt ar15's (triangle handguards) the finish on lower reciever looks like peeling paint.
the ones i had of late 70's vintage didnt have this problen
what was this finish and about what yrs was it used

It's called SFL (Solid Film Lubricant) a kind of graphite based paint that is "the only authorized" surface re-finish for U.S. weapons.

Applied with a rattle can and air dried it is only used at depot level repair and is only to keep the aluminum or steel from corroading. It really isn't much good, as you mentioned it has a tendency to peel and flake off.

Eric

thanks for the reply
i guess a guy could send it off and get it parkerized