I see no reason to cross bolt any caliber less than the 416 Remington, but you could cross bolt a 375 if you wish...

A good glass bedding job will do a better job than cross bolts in any caliber, but I still use them with a 416 up...Definately glass and cross bolt and use two recoil lugs on any gun larger than 458 Win...

My 9.3x62 and my 338 Win have not been glassed or cross bolted and I have been shooting them for many years, but they are custom rifles with proper bedding in good dry cured Turkish Walnut...

Good wood can make all the difference in the world..