I shot a doe in the shoulder with a 165 grain game King. It was shot from a 30-06. The bullet blew up the should but didn't enter the rib cage. The doe was limping off and I had to shoot it again.
If there's a tougher bullet use it. As it is Sierra bullets are now used for prairie dogs and paper targets. I will never use Sierra bullets on game again!
And to show how quirky, a buddy was shooting exact same from his gun, my reloads. Hit a rib going in, a rib going out, through both lungs. And we found a tiny piece of lung on the ground.
Never expanded and never killed the buck.
We know that because it was killed 3 weeks later, shot in the neck so we could see, hole in a rib each side, no expansion, and a bit of scar tissue formed in both lungs already....
although I've never had a bad result from the SMKs, I know others claim to have. I trust the SMKs more than teh game kings.