I'm planning my next build and I'm 90% sure it will be a 6mm Rem AI (also considering the 6mm Super LR). I know Rem and Win make 6mm brass and besides normal brass prep, all I'd have to do is fire form. However, I've found some 5.6x57 RWS and 7x57 Norma brass. Since I've never necked up or down brass (or possible neck turning or inside neck reaming that might be required), I thought this would be a great time to learn. So, of those two choices which would you do and why? Thanks.