Bulldog,

I guess .700 NE in a pistol is certainly "possible". You would have to be careful of the pressures developed and the type frame you choose to chamber the .700 NE. Carefully calculate the pressure and velocity from the combination of type powder, charge, type bullet (jacketed vs. lubed-lead), and bullet weight (and of course the empty portion of the loaded case).

The .700 would be physically too large for the Thompson-Center Encore frame. I'm not sure what base frame would be suitable in dimensions or material strength. I imagine a custom made single-shot or revolver is necessary.

I would be more concerned with the chamber pressures than the bullet velocity or accuracy. (At least initially).

Kamikaze