Remember the environment issue. If I remember my school geography lessons right, Comagutsa's Perth, Western Australia location is a tad

warmer usually than the Perth, central Scotland that I grew up in.
The 8-inch twist provides the full 1.5 optimum Sg coefficient of stability value at 80-deg F 2,000 ft ASL altitude from 3,000 fps MV. On thne other hand shooting on a cold winter's day in North America at say 20-deg F in anticyclonic high pressure on or close to sea level drops the Sg to below 1.2 which could produce a visible deterioration in short range groups, and would definitely affect bullet performance at longer distances.