As I said in an earlier post I had no luck when trying to develop an accurate load with 400gr plain base cast bullets in my 404 despite using Lyman #2 lead mix which performed fine in my 7mm. Recovered bullets showed good engraving and where otherwise undamaged but just would not group. Spun a shoulder on the base of some and applied a 44cal gas checked, sized and lubed and loaded up with same charge of AR2209 (4350) that gave clover leaf groups with 350gr GC cast bullets. The GC 400 grainers gave same excellent results. Some rifles may not handle plain based cast bullets. Not hard to gas check plain based cast bullets.