I was hoping for some help finding info on what has been done on the 404 Jeffery. I only know it parented the RUM family. Remington shortened it, I do not wish to do so, otherwise I would use the ultra mag brass. The general idea is a .338 neck both long and wide with a 35 deg shoulder and minimal taper to be used in a Wby Mk V origenaly chambered in 300 Win Mag. I was directed here by 30-338, on the Reload Board, that fiftydriver may be able to help. Any one that has an idea please chime in! This looks to be a great board and is right up my ally.