I'm kinda thinking like what TA said, something like a modern day ballistic-tip.
A hollow point would'nt travel as fast or as accurate as pointed bullet,especially for a sniper rifle.
The book, " Blood Red Snow" only mentioned that they were "explosive" and this was the actual German talking first person.He was a MG-42 gunner and his #2 man got hit with one. How he "knew" they were explosive, I don't know.