Osgeld:
machined sockets are very tight and I generally dont like them, but you can do itback to the op
use a saw, many hobby and craft stores sell razor saws (large razor blades with teeth), very handy
Well, maybe I just didn't want to force them. They didn't go easily into the machined headers, didn't seem to want to go at all, and fit nicely and snugly into the cheapo headers - a perfect fit, so that is what I use. I got them both from Taydaelectronics.com. The matrices are 60x60mm ones and the pins are relatively sturdy, maybe to mechanically hold the matrix in better. Hopefully it works for you.