i dont use a 3 way cutter , i may be off here but ill throw some ideas out since you havent had any replies yet
if you are you sizing before trimming , your neck is undersized and too small for the pilot , you probably have some brass smearing on the pilot too , maybe you can sand down and polish the pilot to meet the diameter to fit your existing process, or do the trimming before sizing -- you really dont need a tight fit on that pilot , just tight enough to keep it from wobbling
the other thing that would do that galling would be heat buildup from friction from going too fast , are you powering it with a drill ??
then how to fix it , you could shoot it and make sure its a problem you can see and eventually it will work itself out
or, you could probably run it through your full sizer die with expander button in 6 -8 time each then anneal em.
or best way, inside neck reamer would probably do the best job as long as you had a expander that was Barely under the cut diameter , which should probably be annealed after as well