Be interesting to know the total weight of the ejecta (powder, wads, shot) of the two loads which along with velocity are the factors determinant of actual recoil. Gun weight is also a factor but is the same with both loads apparently. It typically takes more powder with felt or fiber wads compared with plastic gas seals due to the less efficient fiber/felt to have equal velocity. The old reloader rule of thumb is 10-15% less of the same powder for plastic. Gil