Crash Bullet

The next time you make a ranged weapon attack during the spell's duration, the weapon's ammunition, gathers an explosive energy around it. On a hit, the target takes 4d8 Thunder damage(instead of the weapon's normal damage), and must make CON save or be knocked prone. On a miss, the target takes half as much damage and is not knocked prone.

After being shot, the spell ends, and the ammunition returns to normal  

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage for the spell increases by 1d8 for each slot level above 3rd.