IMR-4166 and IMR-4451 both have temperature stabilizing and Copper fouling preventing coatings.

If you shoot deer at 100 yards with a 30-30, you don't care.

But if you shoot deer at 500 yards with a 7mmRemMag, this is breakthrough progress.

There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. -Ernest Hemingway
The man who makes no mistakes does not usually make anything.-- Edward John Phelps