Error in my efficiency calculation for FWB rectifier?
The formula you use for RMS voltage applies only to a half-wave rectified voltage. The RMS voltage of a full-wave rectified signal is the same as that of the unrectified signal, ignoring diode drops (which are insignificant at 120V).

This can be seen by observing that the first step in calculating the RMS value is squaring the voltage; x2 and (-x)2 are equal for all real values of x, so after this initial squaring, you can't even tell whether the original value was positive or negative. So the RMS value of |V(t)| is necessarily equal to the RMS value of V(t), for any function V.