Experimenting with a projectile build, I noticed a drastic decrease in overall damage after putting a skill point into Puncturing Shot, which increases all your projectile's pierce by 1. On abilities that normally have pierce greater than 1 such as Deathgazer Railgun or Arctic Spear, this passive worked fine, allowing these abilities to hit more targets. On abilities that normally have a pierce of 0, such as Havoc Orb (with the rocket adjustment) or the basic pistol auto-attack, the projectiles will always shoot past their first target, dealing no damage. I tested this not only on single enemies, but even stationary boxes. In both tests, I could not deal any damage with normal projectiles, but could with multiple pierce projectiles.