hey Mike,
i called and talked to sierra-tech-support and they said yes your 1-9 twist would stableize your 175 MK.
noslers 5 edition manual likes r-22 with 62.5 grains useing their 175 partition bullet for 2970 fps,81% load density,w-w case,fed. 215 primer,a wiseman 24 inch barrel. i'd advise a ladder test starting at 60.5 grains and working up in .5 grain incraments, with that longer bering surface of the 175 mk you might fine max pressure earlier and at the same time find your rifles ...sweet-spot....
regards
