I would guess 1 in 10 twist
All Savage rifles chambered in 250-3000 prior to 1960 were cataloged as being cut 1-14" ROT, while all Savage rifles chambered in 250-3000 since 1960 were cataloged as being cut 1-10" ROT.
I have had good luck with the 75 grain Barnes Original X and believe that it may be the best deer bullet for 1-14" ROT .257" bore rifles yet to be sold in terms of velocity, penetration, and accuracy potential.