Gun Script/shot

Hello i want to make a fps game with Zombies but i don’t know how i can make a gun in unity 5.4
the gun must can hit a cube with a riged body.

i neet a tutorial where i can see how it walkes.

Two official tutorials from Unity contains shooting mechanics:

and

Articles about shooting in both tutorials it is №7.
Direct links:

In addition, if you need ready solution, you may find a lot of it on Unity Asset Store. For example this one:

ok thanks my friend =)