I can not convince some of you that Sierra has an enormous financial reason to not market the Match King as a hunting bullet.
There's a good reason you can't convince people. That theory will never convince anyone who knows the facts and can logically examine them. It is a complete load of crap.
1. The U.S. didn't adopt the Sierra MatchKing bullets for sniping until 1985. If the theory held any water at all, there would have been zero reason for the GameKing line to exist prior to that point. In fact, GameKing bullets were available in the 1970s, years before the military was even considering using the MatchKing line for sniping.
2. If the theory were true, there would be no reason to differentiate between the GameKing and the MatchKing bullets in calibers that are not used by the military. It's simple to verify that there are GameKing bullets available in calibers that have never been and never will be used for sniping.
3. If the theory were true then Sierra could simply relabel MatchKing bullets--perhaps alter them cosmetically--and sell them as GameKing bullets and nobody would be the wiser. They could use one of the high-tech coatings on the bullet (like the black coating Winchester puts on some of their bullets) to make them appear very different. It's simple to verify that is not the case. The GameKing bullets clearly differ from the MatchKing bullets in construction and often they aren't available in matching bullet weights.
4. If the theory were true, then any changes made to the specific MatchKing bullets that are used for sniping would eliminate all need for a coverup. It would be sufficient for Sierra to point out the fact that in the mid-1990s, the specific MatchKing bullets used by the U.S. military were altered by Sierra in cooperation with the military to meet the military's specific requirements. Being able to accurately point out that those bullets are not the original MatchKing design but are specialized designs made to accommodate the military would effectively dismiss any concerns about violating ammunition conventions.
5. Finally, it is a complicated explanation for a very simple question that has been given a very simple answer by the manufacturer. An answer which is supported by the available facts and logic. When the facts and logic support a very simple answer, there's no reason to go looking for a complicated one.
So if we are to believe the theory, we must accept that Sierra anticipated the use of their MatchKing line for sniping by many years and introduced the GameKing line as a cover story just in case the MatchKings were ever adopted by the military.
We must further accept that to make this cover story airtight, Sierra also introduced GameKing bullets in calibers that have nothing to do with sniping and again did so years before the military was considering using MatchKing bullets for sniping.
We must also accept that Sierra then went to the additional trouble to make the two bullet lines different by altering construction and bullet weights even when they could have very easily made other, simpler, much less costly changes that would support their story more than adequately.
And we must accept that even though the specific MatchKing bullets used by the military have been altered from the original MatchKing offerings, Sierra, for some unknown and illogical reason decided to keep supporting the alleged coverup.
The theory is factually and logically bankrupt which is why it is not convincing.
I think the better question would be "Why would I use anything but the best?".
The fact that you can ask this question, honestly believing that the question and answer support your argument, is more than just a little bit amusing.
Your question is a good one. The answer is that it doesn't make sense to use something that isn't the best, something that isn't designed to do what you want it to. In this case, the manufacturer tells you which of their bullet lines is the best for hunting and which one shouldn't be used for hunting. That makes the decision so simple that it hardly even qualifies as a real decision.