I was doing some reading the other day and the author made the statement that the newer controlled expansion bullets have made the long, heavy for caliber slugs obsolete. He specifically stated the .30cal rounds like the 165 and 180 gr TSX and TBBC (although I assume we could be discussing any similar rounds) have replaced any need for a 220gr RN.
When I shop for ammo I rarely see any 220gr .30cal ammo or any .338 ammo heavier than 225gr. although both used to be very common on the shelves. I do find plenty of controlled expansion ammo in lighter weights though.