UNDOCUMENTED MECHANICS
2 frames (0.1s) between missiles. Damage is per missile.
The missile travels 12 yards.
It stays out and keeps hitting, but the same target can only be hit again every 10 frames (about 0.4s). The listed damage is per hit; this gap sets its real rate.
On impact it spawns a second missile; that damage is not included in the figure above.