It's too close to the season to switch calibers. The learning curve of a bottle neck case in the Contender can be steep, and the Herrett takes extra time for case forming, trimming.
Both Herrett calibers can give much personal satisfaction when mastered, and will expand your knowledge in many areas, from annealing brass before you form the first case to doing your own trigger job, talent that stays with you.
In the 357 Max I have been using Nosler 158gr HP, Federal 205 primers, and Reloader 7 in a 14" bbl..