I have been purchasing wire from McMaster Carr for this for some time. The best wire I have found is Oil Hardened wire .107 in diameter. I have used .125 in mild and hi-carbon and even stainless and I have experienced a work hardening effect at the start of the thread. This has been a fracture point in one case. The best method and control rods that I have found are the oil hardened wires .107dia run through a "QUALITY" die nut with a lot of tap magic. I screw the wire in the die with a cordless drill. I have made bunches of these and their on My 40% EDGE. If you are interested I can come up with a e-mail and part # from Mcmaster Carr. Music wire and the KS stuff is too hard. By the way, I think the E70 and E71 series stuff is to soft. JMO