I have painted five of the 1/64 collarless heads, and in messing with them, I have seen that they are a hard lead, by scraping any excess around the eyelet leg with a pocket knife you can just tell it's hard, and shiny.
they must use some type of pressure system to pour those with that hard lead. anyway, it suits me fine because you don't get any loose heads that wiggle around on the hook, because the lead is stronger.