Okay, here's the deal: FMJ's are the only rifle round legal in war. Da guy who came up wid da .223 got around that by making a cartridge so hyper fast that the bullet does something that seems quite unbelievable. When the bullet hits a solid the front end slows down but the back end of the bullet is still going unbelievably fast and the result is the same as a car skidding on ice. The bullet starts to skew or tumble creating a much larger wound than its diameter. It acts like a dum-dum or soft-point, both of which are illegal to use in war. There is no reason to shoot a soft-point .223 under the mistaken belief that it will mushroom. It doesn't need to mushroom to do the incredible damage that it inflicts. It's a little weak at longer ranges (250+ yards) because as it slows down it loses the ability to tumble. Incredible round. In Arizona, we can use a 30 round clip for hunting big game if we want. Only use that if you want venison hamburger.
The Hague Convention of 1899 prohibited the use of expanding bullets in war. Not all countries signed that treaty. Big game hunting is not war.
Ethical big game hunters want a quick, humane kill. Expanding bullets make a larger wound channel and transfer more of the bullet's energy to the animal which causes greater tissue damage and trauma than a FMJ bullet which may just pencil through the animal. Soft point, plastic tipped, and hollow point bullets are designed to quickly open up or mushroom, even at lower velocities.
Any caliber FMJ bullet might yaw if it enters soft tissue at velocities above 2300 fps. Then it may or may not tumble and may or may not break up. Below 2300 fps it will probably just pencil through unless it hits something solid, like bone.
The 62 grain FMJ ball military version of the .223 Remington at 3100 fps is not quite what I would consider a "hyper fast" cartridge. That velocity has been attainable with 130 gr bullets in the .270 Win for over 75 years and almost attainable with 150 gr bullets in the .30-06 for over 100 yrs. There are a number of other .22 centerfire cartridges that easily shoot 36-45 grain bullets at over 4,000 fps.
And finally, anyone that needs a 30 round clip to hunt big game needs to first learn how to shoot, and second learn how to hunt close.