Which one fit better in the context of "Complete the next mission"
Hit enemies with bullets 50 times
or
Hit enemies with projectile 50 times
All bullets are projectiles, but not all projectiles are bullets. A cannonball, for example, is a projectile, but not a bullet. On that context, it could be confusing. Consider that even a little stone thrown by hand is technically a projectile.
In that context, and without any more information, I'd rather use just "Hit 50 enemies", unless an enemy can be hit more than once before dying.
