http://www.youtube.com/watch?v=0jgnId0taNI
As you can see the bullet dispersion is way too high, it doesn't even look right. While it is understandable that there is no need for this gun to be accurate, there is no game value in such poor accuracy.
Basically it is fun for 3 seconds and wasted resource after that, as one can only use it to launch flares, if you are lucky. Why not to make it accurate or fairly accurate? To make it shoot left when you want it to shoot right is much easier with a script tweak than to make it shoot straight at current condition.
If it happens to be design decision, maybe a child class can be created with better accuracy, hgun_Pistol_Signal_F_Scripted?