I have to agree on Shilen's recommendation on a 9 inch twist for 117 and 120 grain 25 caliber bullets. My custom .257 Roberts 3 inch chamber with a 10 inch twist Shilen barrel has shown a marked preference for 100 grain bullets. Compare the 110 Accubond, 117 Sierra BT, Nosler 120, to any 100 grain bullet and you'll see how long they are for their bore. Mine will shoot them acceptably, but will put the 100 grain Sierra FB into very small cloverleafs. If was to do it over again I would go with a 9 inch twist if I primarily wanted to shoot the heavier bullets.
