I've had nothing going but good luck with Gameking bullets, I've even used them on elk. I almost always have a jacket and core separation, but I've never had one explode. Usually I find the jacket in the hide on the off side, but the core has continued out and not been recovered.
At the speeds the Grendel produces I'd not be afraid to use a Sierra bullet, but I'd probably opt for the Prohunter for the shorter OAL of the bullet when magazine space is limited. Plus the Prohunter doesn't seem to have jacket separations like the Gameking. Most people attribute the jacket separation on the Gameking to the boat tail design.
At the speeds the Grendel produces I'd not be afraid to use a Sierra bullet, but I'd probably opt for the Prohunter for the shorter OAL of the bullet when magazine space is limited. Plus the Prohunter doesn't seem to have jacket separations like the Gameking. Most people attribute the jacket separation on the Gameking to the boat tail design.