That actually sounds really interesting!
Slice off .308 brass at the shoulder, and a .429 bullet fits pretty nicely. Rimless, feeds through the same bolt actions that run the .308, and a Savage 110 with the barrel nut can be headspaced in a matter of minutes. I've got chamber reamers and a set of case forming dies a friend had custom made for the round, which shall remain nameless in case he decides to go into production. I've built up a few rifles for him, and they drop deer like the hammer of Thor.
Didn't Desart Eagle do something like that at one point?
Another interesting one would be the 35 Remington necked up to .429.
