Thanks for the replies, guys. I don't have a mill, only a drill press. But it seems like it would make life easier if I get a vise for my drill press. I think i'm going to go the route of the .250" end mill instead of the counterbore. Again, thanks for the responses.
I bought some of the chainring bolts to try on a knife for the first time. I ordered the ones that are 3/16" dia. with the .249 dia heads. What are you guys using to countersink the heads? I'm going to be using them on a G10 handle scales and the blade and scales are already drilled to 3/16"...