Is it possible...

...to give the rpg the model of a pistol so it reloads faster but still have it shoot rockets? Im not not thinking about it having the ammo of a pistol, just the draw speed and reload speed.

No... All you can change is the Model and RoF.

That's exactly what he is asking for. Faster reload and RoF and draw speed. I'm not sure if you can switch models with a launcher and a pistol though.