I have shot many rilfes chambered in 300WSM and the majority of the Manufacturers use a 1:10 twist in barrels for this caliber.
The exception is the Sako and Tikka barrels which are all 1:11 rate of twist fopr the 300WSM's.
I did a lot of load development for a Tikka and a Browning and loaded both 150's and 180's for them both.
The Tikka was slightly faster and slightly more consistent/accurate in both bullet wieghts and with all loads. I cannot say this was due to the rate of twist or to the slightly longer barrel or some other reason... I have no way of knowing.
I can say with certainty that the Sako and Tikka's perform very well with the slower twist using 180 grain bullets. The Browning was no slouch either with the faster twist.