I am starting my first wildcat project. I am having a fully chambered 7mm-300wsm being built and I want to neck down 300 wsm
cases to 7mm (this is not just prepping 300 wsm brass to eventually fit a 7mm wsm
My usual new brass prep (not specifically in this order but...):
Norma brass preferred, winchester as a last resort
sinclair expander mandrel
flash hole debur
sorting by neck variance (keep cases with < 0.0015)
weight sort (remove top and bottom 5%)
neck turn to uniform neck thickness
primer pocket uniform
trim to uniform length
polish w/ 0000 steel wool
I need input specifically regarding:
Should I neck turn the 300 WSM, followed by necking down to 7mm
Neck down the 300wsm and then neck turn the 7mm after case forming?
I will be using redding S type FL sizing dies w/ bushings.
What increments should be used to minimize work hardening?
Neck ream to minimize doughnut? When?
Since this cartridge is not uncommon, any help/experience is appreciated.