What I have found is that being 50ft or so above sea leve, the long high bc bullets work best with an extra half a twist above minimum. If you check bergers stability calculator you find that a lot of the "max" bc bullets for a caliber are only marginally stable in my conditions with the minmum twist rate recommended by the manufacturer. That is why I run 7.5 twist in my 6.5 PRC, 6.8 Western, 7 twist in my 6CM, 8 twist in my 7 SAUM, 280 AI and 30 Nosler. The 6.5 SAUM I just bought has an 8 twist, I am interested in how it runs the 153.5 berger hybrid that just showed up my door today, amongst this biblical style monsoon going on in the mi-atlantic.