Hi Jeff... glad to see you posting! Yes they used to add lead and brass to the clay to make them heavier. I have and old RAS 300 chip monogram set that you might like. These weigh 10 grams and they are square edge composition chips. All of the chips are in great condition with only minor "flea bite" nicks on some and no scorched chips. There are 150 White, 75 Red, & 75 Blue chips and I think the set is missing a white chip and maybe a red one too. I will make an acurate count if you are interested in them. These were probably somebody's personal set and they are old I would guess from the 30s or 40s. They are in a 12 hole round rack that is in very nice condition. I need to get $100 for the set plus shipping. My camera is broken but I can bring one home from work tonight and send some pix.