One of the very last things I did before retiring from EMD was to wander out back in the yard with a coffee can and scoop up some machining turnings or chips, as they were called, for my scrap loads.  They were pre-weathered with rust and I use them as loose loads in my gons.  Repeated pouring and dumping them out of the gons also has the benefit nicely weathering the gon interiors.

Bill Darnaby