matrix 165gr. in 270 WSM with VihtaVuori

[10point]

I shoot a 28" Kreiger barrel with a 1:9.5 twist and a 700 Remington action. Developed an accurate load of 68 gr. of N570 VihtaVuori and a 165gr. Matrix hunting VLD at 3065 feet per second at 100 yds. I got a sticky bolt at 70 gr. of powder and 3150 feet per second. I am going cow elk hunting late January 2013. I am concerned about velocity and accuracy stability at 9000 feet and 20-35 degrees F. The load was developed ast 2700 ft elevation and 65 degrees F.