I was wondering if there is any way to clean these marks off of slides and recievers.

It doesnt bother me so much on my AR15, but I just bought a new HK USP 40, and after 150 rounds, I already have brass marks on the slide.  Same goes for my 1911.  

Is there any way to take them off, or is it a lost cause?

Thanks,
Scott

Cold blue will take them off... But they will be back and most of us dont worry about them.

CLP + Toothbrush + Elbow Grease will get rid of most if it.

I kind of like the marks on my AR15 and FAL.  Gives it character.  But...on my brand new USP, it sort of bothers me.  I think its one of the best looking guns, and would like to keep it as nice as possible.  Same with my 1911.  The parkerizing really makes them show up.

My Beretta is the only gun which doesnt have shells bouncing off of it, so its not a problem.

Anyways, I will try the the cold blue stuff, or the CLP.  Will the cold blue stuff affect the finish on the HK?

Cold blue is OK where steel is bared by contact, but be sure to get it all off and protect the spot with oil or you'll get rust.

As for actual brass spots, just use Hoppe's and let it sit.  But why bother?  Overclean and you'll hurt your stuff.

Sweet's copper solvent seems to do a pretty fair job of getting rid of the brass marks.

to keep them from getting marked, i use a piece of black electrical tape---after you shoot remove it and presto-----no brass marks    JIMBO