For this week's assignment, you will continue your assumed role at a gunsmithing organization. The customer from the week 5 assignment is so happy with the modifications to his Remington M700 rifle, he has decided to request a few modifications to his Remington 870 shotgun.

The customer has requested the installation of a choke to give him 45% shot charge at 40 yards and is considering the installation of ventilated ribs to "add some value" to his favorite shotgun.

Describe the purpose of the choke, the process used to install the choke, and the installation procedure for the ventilated rib.