I've been thinking of a new round. I want to take a .378 Weatherby Mag., shorten the neck to .350" and fire-form the shoulder to either 35 or 40 degrees. I would load these with 330gr. Lehighs. They look pretty good with a .941 BC. I've thought about instead using .416 Rigby brass as an alternative and necking it down and fire-forming it so I don't have to worry with the belt on the Weatherby Mag cases. Or I could just turn the belt off. The reamer print I drew up is without the rim. I just want some type of feedback. Has this been done before? I'm sure it has, but I'm having a hard time finding any info if it has. Thanks in advance.