RE: How are Sierra bullets
I have used the Sierra 175 grain Spitzerpro hunterin my 8mm-06 for years and have been very pleased with them. Accuracy is superb and I have never had any issues holding a deer with them.
According to Sierra, the gamekings are generally designed to be used as a long range bullet while the pro hunter is generally used at more moderate ranges.
Honestly, I believe Nosler, Sierra, and Hornady all make fine good quality bullets.