The Lee Collet die has changed please be aware
https://forum.accurateshooter.com/threads/lee-collet-die-fyi.4005584/
A general rule if you are reloading like Peter wrote seat a bullet in a dummy round and measure the outside dia. for 308win it will be .338
If you want to take it further both Lapua and Norma brass (sampled) have neck thickness about 15thou (15 x 2) + bullet dia (.308) = .338 you can substitute this with any caliber size. 2thou under for 308w is .336.
Peter sells Whidden bushing they are higher quality and are more concentric and true to size. you can also by Redding (but get the TIN versions) Redding also comes in sets.
Save yourself some aggravation and by two bushings 2 and 3thou under. one of these will show better accuracy. The USAMU suggests starting with .003thou neck tension (article on Facebook)
Cheers
Trevor
