Sorry guys, been away hunting, didn't find your queries till now.
Its the 7mm/404 imp that pushes the 180gn Berger moly at 3400fps out of a 30" plus barrel, using RWS brass. Kirby's 7mmAM has more capacity and will easily beat it in the Lapua brass.
The Fatso is a WSM length 7mm/338 Lapua and is more like the 7mm STW ballistically, but does it in a short action.
I'll run a sizing button 4 thou under loaded round neck diameter to get the neck tension I want to jam a moly'd Berger in the lands, where they shoot best in my guns.
284, sounds like maybe your barrel doesn't like the heavy bullets, but I'd still try the 180 VLD jammed and the 162 A-Max just touching to be sure.