Originally Posted by Broz
Necking down from .308 to .284 I doubt you would have any neck thickness issues. I hate to go against the advice of your smith, but if it were me I would be getting some 308 Lapua brass and necking it down. We do this all the time with 300 win brass necked down to 7mm for the 7-300's. Same sizes and process.
...aaaaand, if you're worried about the necks being too thick, you can buy some Lapua 260 Rem brass, and neck that up, instead.