I asked Redding the same question (Competition set). They told me to use the Ackley dies for seating. I've done it a bunch and never had a problem. Sizing should not be necessary assuming it is virgin brass.
i use the ackley seting die.. you could even use a 7mm mag seating die if you really wanted to... but thats another story. I fireform all my nickel brass with load touching the lands. less case movement and it works very well. !!! good luck