The new poly tips are good for ballistics and perform well on small game. They aren't meant for heavy game. other types are meant for elk.
Your overall post was good,we disagree a bit on this point.
Frankly,I've never hunted elk with factory loads.Started rolling my own in the late 60's.
I do not have Cor-Loct Remington experience.Apparently,they do the job.
I grew up reading Elmer Kieth wtite about Western Tool and Copper bullets froma 333 OKH ,busting the south end of a northbound bull. I'm thinking a busy man who needs meat has his own way of doing things.
If you have the luxury of choosing a shot through ribs into the boiler room,a 308 shooting a 165 gr Nosler Ballistic Tip will work just fine inside 300 yds.
So would a 15 grains of lead heavier 180 gr.It will open up and soup the heart/lungs.
And there are the Accu-Bond and Partition options.
I'm not knocking the Remington Cor-Lokt ammo.I'm sure its worked fine for decades.
I'll say it this way. Few would argue with a 130 gr Cor-Lokt from a 270 being adequate for this cow elk. But its not for blowing holes through something brown crashing through the trees. It works hitting the boiler room.And frankly,so will a .243 properly loaded.
If you can place a shot a 165 gr Ballistic Tip works fine.So does a 180.
No doubt either Cor-Lokt will also do fine.
The 308 is not extreme.That helps it be dependable.I'll agree that too hard of a bullet may not work as well.For myself,I'd probably choose the Ballistic Tip over the Accubond.