I totally agree; the Weapon Modification should have more options, such as the extreme recoil you get from a shotgun pellet with high speed. It would be nice if you were able to get such a recoil without using the shotgun pellet. (BulletStyle=3)
Suppose you haven't tested using shotgun pellets with high speed, I suggest you try it.
And whatever, what's already said, changing semi fire to automatic and vice versa. Scope, lasersight (customizable image), etc. Being able to choose the amount of bullets in one semi shot, etc etc.
Any Weapon Mod updates at all would be great. F12!