I would FL size them but I wouldn't bother trimming them until they have been fired once.

I've bought new unfired WInchester brass in 223 and 270, and to get consistent bullet tension, they all had to be neck sized at least (I ended up running them through the F/length die anyway, and trimmed to length.

Case lengths were very variable!!

Been having some problems with once fired brass in my 243 WSSM so i went out and baught a hundred brand new un fired brass. Do i need to full lenght size this brass? neck size?
or just trim prime powder and load?
Thanks very much
CdnWalleye