Hi TJ,
I couldn’t recreate it in a test project so I fiddled with my main project again to get a better idea of what was going on. It turns out the change I made that mattered was that my BeginPlay in MinigunProjectile called its parent (TurretProjectile BeginPlay). The TurretProjectile BeginPlay sets the projectile initial velocity. It turns out they were spawning but not moving because the TurretProjectile BeginPlay was not being called from MinigunProjectile.
So I think the real bug is that my child class is not calling its parent BeginPlay unless I explicitly tell it to even when the child hasn’t overridden it. This is happening when I build for Shipping with blueprint nativization on and pak compression off.