Download Bullet Impact Sounds Free Unity. 

It contains 153 bullet sound effects (23 bullet flybys and 130 bullet impacts).

Bullet impacts cover 16 different surfaces. Body Flesh, Body Thump, Concrete/Brick, Dirt, Grass, Rock, Gravel, Glass, Metal Light, Metal Heavy, Wood Light, Wood Heavy, Water, Mud, Snow and Ice. Each surface has 8-9 sound variations.

View the full sound list HERE and be sure to listen to the audio preview.