How to cancel left click swing animation with item in hand.

I'm making a gun mod. I was able to turn the animation used for right click off, so when I shoot my gun it shoots and does not swing like a sword. I want to make a procedure so when the player left clicks with the gun it will fire, but I need to make the left mouse click swing/attack animation turn off so I can shoot the gun with left click. I'll make a invisible quiet projectile with very little damage and almost no rage so the right click won't actually be used to shoot the gun but rather aim the gun instead. How can I turn off the left click animation?