Forming 300W / 300BO from .223 / 5.56

For those who have made cases for 300W, do you have a preference in parent cases? - Not really, whatever I have that is one lot number and I know the number of times they have been fired. 

Do you choose Commercial or Military? - Lot numbers, a large enough sample whether commercial or military that I have some extra to use setting up  I prefer commercial, but good military brass is acceptable.. 

I weighed one SSK casing that was 84 gr. Do your cases mirror that weight? - uniformity of weight, say +/- 2 grans, is more important than weight. Some military issue bras will come very close. others will not.

Mine are to be used in a TC Contender 10'' (SSK barrel). - Factory chamber? Setup using the chamber to assure headspace is tight, but the T/C ill close easily.

Did you anneal?  - Always is more than two calibers difference. I once worked .348 Winchester to .50-110 WCF which cured me from buying calibers I cannot make in one pass in the sizing die. 

Did you need to ream necks? - No. The reamer will follow the least resistance in the hole and not even out the neck walls. When needed, I outside neck ream since this removes the high spots.