The original xp-100 was a good design and a dandy pistol. One they dropped the .221 chambering and went to the .223, it was very short lived, mostly because it didn't make sense.
These don't make sense either. (with exception of the .300 BLK)
Why not use the model 7 action?
Why not chamber it in cartridges designed around a 10.5 inch barrel, like the .221, .300 blk and the other whisper cartridges?
The barrel is 10.5 inches and will come in 300 BO. Not sure why anyone would want a 12 inch .308 but to each his own. it's a 700 action, build it any way you want if you really have to. Brace it, and you'll have one handy camp "pistol".