I have to do the same thing when I switch between 38spl and 357 magnum. Reset all the dyes. The directions for the dye set up is for .40. Resize de prime should be the same, but powder and seating dyes have to be adjusted out for the longer case. The flair happens at the same time as the powder dump. The case pushes up against the flair mouth as it pushes the powder drop into the case. When you reach the top, its flared and filled.
EDC G27 Virginia CHP holder VCDL member-Glad to have them fighting for my 2A! Nra member