I called Hornady and asked them about it what twist would work when I was buying a blank for my 6mm-WSM. The Hornady Tech stated that 1-9" was optimum for the 243 types of speeds which he stated were tested up to 3000fps. I asked about the 9.25 Savage twist while I had him on the phone (I waited 15min so I figured I'd hit him with a few questions) since my 243AI is a rechambered Savage SS Varmint Barrrel, and he said the the .25 twist difference according to his data should not make a difference, but he said he wouldn't run them slow.

Take that for what its worth.