I remember they are 20 tpi, and at some point went from RH to LH threads, maybe at 760-7600 transition, the rh threads had a nasty habit of unscrewing from bolt rotation and creating phenominal headspace problems, one of the reboring guys, does almost all calibers out to 358 win, or 35 whelen, depending on long or short, the job runs 225 as I remember, not bad for making a woods thumper!