I've Had JES re-bore and chamber two rifles for me a 9.3x62 bolt gun and a 358 lever Browning. Both shot much better after his work. They are keepers. I always go with 5 grooves and with the 338x06 I would choose a 1-12 twist to stabilize the 250 or heavier longer bullets--- your call on the twist.
He has the rifle back to you in two weeks--- and even sends two fired cases back to you for inspection and to help set dies-who else does that?
get it done before he retires or quits!
Good Hunting
Lj

Last edited by Heavybullets; 11/13/17.