  In this contribution, we show some recent progress in the study of
neutron-proton scattering with Nuclear Lattice Effective Field Theory (NLEFT).
We present preliminary studies of both, the uncertainties in the $np$ phase
shifts extracted with NLEFT, and the lattice spacing dependence in the transfer
matrix formalism. Such investigations have not been performed before in the
literature, and will be relevant for Monte Carlo simulations of nuclear
structure with NLEFT.
