I have no experience with the Game Changer in game, because I haven't been able to make an accurate load with any of them yet. I WANT to use them on deer, but haven't found the proper technique to get MOA accuracy from them yet. If you have any secrets on loading them accurately, I am interested in learning the technique.
You have to remember that every gun is different and yours just might not "like" that particular projo, no matter what you try to fix it.
Move on to another bullet style, weight, manufacturer until you get that Goldilocks fit of "Just Right" for YOUR gun.
But before condemning the projo in question, make sure all gun/scope/ring screws are tightened to the appropriate torque per the manufacturer's specifications, your barrel is either perfectly free-floated OR has the appropriate amount of barrel/stock touching/interference (some gun/barrel combinations actually need some touching, my Winchester Model 70 in .30-06 being a perfect example. It shoots 3/8ths inch groups all day long with a homegrown load) that you can only determine after MUCH experimentation and expenditure of bullets/powder/primers (YIKES) and time on the range.
Among the myriad of things to tinker with is the leade in barrel and how much "jump" you want to use or NOT use. This is also something that is non-specific and only determined after experimentation as each gun is different.
And don't forget one of the MOST important aspects of searching for Goldilocks, that being the muzzle crown.
Look VERY carefully for any kind of aberration to the muzzle and, if possible, have a qualified and experienced gunsmith crown or re-crown the muzzle to eliminate that part. And while the gunsmith is checking that out, ask him to look at the interior of the length of the barrel for excessive leading or copper deposits using a borescope. Either/both can raise havoc with accuracy but like some other aspects, this can only be determined by using the correct equipment.
You can buy a decent borescope these days but as with so many other things, you get what you pay for. Better to buy once/cry once and get a QUALITY borescope as long as your budget (and wife-unit) will support it.
Good luck in your quest, Pardner. Unfortunately for the novice shooter (not implying YOU are, so no offense intended, Sir) all those things I mention above can be daunting to consider.
But taking the time to work up a good load and ensuring your rifle is in top notch condition is very rewarding.
Some find the journey to extract the maximum accuracy a real PITA, but assuming you don't have a factory lemon, the journey is fun and the knowledge you acquire will help you for the rest of your hunting and shooting career.
I wish you the best of Luck and Good Hunting, Pardner!