For Auto, Triple, or single, you can use loops to determine how much you should fire.
For creating a bullet, you can clone some part to act as a bullet and use force to move the bullet from one place to another.
For a scope, you can use unions to create some sort of modeled scope. It’s best to experiment around with different “parts” that Roblox provides.
For animation, I recommend using Moon Animator for your animations. For it to be “good,” it will require a lot of practice and time, though time is subjective as it follows how well you animate.
(fire modes) take user input maybe the v key to switch a variable that determines what happens when the mouse button is held with the gun equipped
use instance.new() to create a part at the end of the muzzle and tweenservice to fire it down the barrels direction vector raycast for hit detection or fire it towards mouse.hit
viewport frames for scope
and make an animation on the gun and run the animation whenever
this really aint a 1 job thing this requires good scripiting and animating know how to get done you could probably finid a good tutorial online for guns if thats all u want but in reality the best way is to build up your skills in scripting, animating and modelling/building