The use of Sierras for hunting is full of contradictions.
I have killed a huge pile of big game over the past 40+ years with Sierras, mostly GameKings, including many African animalks, and have yet to encounter a major problem. In fact, 130 GK's are what I started hunting with in my first .270 Winchester many years ago. According to many that's a combination doomed to failure, because they'll come apart.
I have seen quite a few bullets separate jacket and core over the decades, but in all but two instances it apparently occurred only AFTER the bullet penetrated the animal, because the jacket and core were found lying together under the hide on the far side. And those bullets included a bunch that WEREN'T Sierras, including just about every cup and core made in America, including one or two Hornady Interlocks.
The only two bullets I've seen leave the jacket somewhere behind the core were a 130-grain .270 GameKing and a 105-grain Speer Hot-Core. Both were shot into eating-size buck deer, and in both instances the jacket stopped right under the hide on the ribs, while the core kept on going and killed the deer.
In the past decade the Sierra I've used most is the 7mm 160-grain GameKing from the 7x57, handloaded to around 2650-2700 fps. Have used it not only on deer-sized game in North America (and never recovered one), but on a bunch of Africa plains game of about the same size. The only one recovered over there was a finisher from a warthog that was lying unconscious and obviously expiring, but still breathing. The finisher was put into the chest from about three feet, and jacket and core were found lying together under the hide on the far side.
A long-time outfitter I know in eastern Montana personally prefers the same bullet in his 7mm Remington Magnum, not only for his own pronghorn and deer hunting but for finishing off deer his clients have shot with premium bullets. Some of those aren't shot too well, but some are shot OK and go a long ways because, he says, too many of his clients use premium bullets that don't do enough interior damage. He's a handloader who's very well acquainted with big game bullets and cartridges, and I always find his comments based on plenty of observation and experience. Craig Boddington is also fond of the same combination.
Another point is that Sierra hunting bullets, like all hunting bullets, differ enough in construction in various weights and calibers that it's not always relevant to make generalizations about performance from 6mm's to far larger calibers. But that's exactly what many (if not most) hunters tend to do, if they've gotten beyond the stage of believing the cartridge is the main factor in "killing power."
