Bruce,

Are the 375 Ultra Mag cases your using for the 404, factory new? Are you doing anything additional besides running them through the sizing die? Does the 375 case require any fireforming for complete case development? As to length, as it comes out of the sizing die, is trimming necessary?

Looking forward to your test with the 416 slugs.

Roger QSL

Yep I got a .418 404. I tried a .416 load in it. I simply resized as usual with a 404 FL die. Then ran it through a 416 rigby die. The difference in length of the two cartridges was about right to resize the neck only. The only problem was, predictably, not great accuracy. It was a blind alley for me and my rifle. Custom made bullets and GS custom .418 bullets was my answer.