Different types of bullets

I thought of a good idea.

To be able to buy different type of bullet for our gun,for example:

Regular m9 bullet clip does 20 dmg in chest,but silver or magnum bullet special m9 clip does 30 or 40 dmg.

It can be zp or gp,permanent or no permanent.

Like the extra clip you buy now but instead of extra bullets you get more powerfull ones.

Or a more extream idea is for bullets to give special effecs like paralize etc but i think thats too much.