There are fed rules regarding ivory.
However, I believe Walrus Ivory is exempt. The reason being, the Alaska natives on the Bering Sea, depend on walrus for food.
There are few jobs in the villages and a lot of these people supplement their meager incomes carving Ivory.
I'm not sure about the rules for non-natives possessing raw ivory, but if its been carved and sold by natives its legal.
I was the XO of the AK NG Native unit on St. Lawrence Island. When I left I was presented with a carved Ivory Hunting Village, mounted on a vertebra of a whale. When the feds adopted their ivory rules I was concerned about my "village" but found, since it was walrus ivory (not too many elephants in Alaska) and carved by natives it was legal.
If one is concerned about the grips being slick, they could engrave the grips which would help a lot.
Its been a long time since I lived with the natives on the Bering Sea, and lost my contacts, but I wouldn't mind getting a set of grips carved for a couple of my revolvers.
My village: