There are two books you guys may want to consider (Christmas maybe?)
As noted, Cartridges of the World lists most everything that's been developed. If you think you've got a new idea, you can go to that book and find out that someone has most likely done it.
The other, The Handloader's Manual of Cartridge Conversions has about every wildcat you can imagine.
Simple physics comes into play with a lot of these hyper velocity rounds. A 10% increase in powder capacity typically only gives a 2 1/2% increase in velocity. The extra energy goes into burning up your barrel quicker. Years ago, the guys at Handloader Magazine made up a (IIRC) .416 Rigby necked down to .22 to try to exceed 5,000 fps. I believe barrel life was less than 100 rounds.
Also, no matter how you reshape a case, a given ratio of powder/bullet weight/diameter is pretty much going to be the same. Calibers like the BR's do a little better, but in the end it washes out close.
The WSM series tried to make you think they had some magic formula for effeciency. All they did was stuff a faster powder into the case and run at increased pressure to get very slightly more velocity. This all comes at the cost of more muzzle blast, sharper recoil, and shorter barrel life. Barrel life may not be much of a factor as I suspect that most of them end up sitting in a gun cabinet instead of actually being used.
In the real world, changing the shoulder angle by a few degrees is pretty much meaningless. A .30 bullet @ 2,700 fps kills an elk just the same no matter what magical caliber launched it.
IMO.....If most guys spent their time practicing instead of dreaming up new calibers, they'd be better shooters. But, I suppose it gives one something to do on a winter's day.
