Call Dave Kiff at PTG and ask for the .295 neck, .160fb. reamer.
I have three of these being shot at the Ridgway varmint benchrest
matches,(850yd crows,900yd chucks,950yd bobcats and 1000yd coyotes)
One of them won the 2 day 80 round match last year with 140 Hybrids though you can still use the 123 Sierras.