I had mine at 60 on the 6.5 CM. I don’t think that 60 contributed to the stock cracking.
If anything, apart from a flaw in the wood, I am inclined to blame some of the factory ammo. Some of the S&B factory loads had some slightly hard bolt lift. The Fiocchi 129-grain PSP had some hard bolt lift and extractor marks. I noticed that the day before yesterday, but since I wasn’t going to use them again, I didn’t think anything more of it. I have a hard time believing that a factory load in a 6.5 CM would crack a stock absent a flaw…
I left it alone on the 9.3x62 (I just haven’t bothered to tinker with it yet).