Don`t really remember if snowballs did a damage on players, but we did many snowball fights, making "fortresses" out of wooden blocks, 1 regular block and 0.5 high slab, crouching behind them, 10 meters away probably. 3vs3 people. The zeds got envious pretty quickly, but they got some, too.
Also, try it in real life, always. Yes, I am almost 38y/o. Doesn`t matter