In a bowl, mix first amount of Frank's RedHot Sauce and buttermilk. Whisk well to combine.
Add chicken and turn to coat well. Cover and refrigerate for at least 1 or up to 6 hours.
In a bowl, combine first amount of flour and Frank's RedHot Seasoning. Whisk well to combine. Drain 1 breast at a time from buttermilk mixture and cover in Frank's RedHot-seasoned flour, packing to form a thick coating. Repeat with all the chicken and allow to rest to hydrate until coated chicken is somewhat wet.
In a bowl, combine second amount of flour, salt, and pepper. Whisk well to combine. Place damp chicken breasts in salt and pepper-seasoned flour and pack well to form a thick coating.
Combine second amount of Frank's RedHot Sauce with melted butter and warm for service.
Set Fryer to 375°F (190°C). For each order, fry a breaded chicken breast to internal temperature of 165°F (73°C). Drain and brush with 1 1/2 tablespoons (22 ml) buttery Frank's RedHot mixture.
Plate bottom of bun, top with chicken, 3 pickle slices, and cover with top of bun. Serve immediately.
For extended meal periods, consider applying the second coating of flour to order for breading consistency.