For forming 35 Whelen brass I like to start with 280 Rem cases.
All of the 280 cases I used were once-fired and all formed perfectly in one pass with no losses.
The 280 has the shoulder a little farther forward than the .35 so just size them to fit the chamber with no worries about headspace.
My Model 600 shoots adequate groups with several 225 and 250 grain bullets but is at its best with 250 Partitions.
8208XBR is my favorite powder but Benchmark, Varget and 4166 also work well.
Cheers,
Walt
