I just asked Sierra the same question about their new 175 SMK (would the 175 SMK work in a 9-1/2 twist in a 7mm rem mag)
The engineer's reply was at first no, it wasn't recommended for 9-1/2 twist @ 2900-3000 (roughly 7mm Rem Mag speed), they didn't think it would stabilize adequately. He recommened that I try the 168gr SMK instead.
He then emailed me back a few days later, saying they did have some promising results with this combo, and that he would let me know what they found in a couple of weeks after further testing.