N-310 is too fast for 38 special . 2.9grs of N-320 or 3.6grs of N-340 are much better loads with the 148 wadcutter . If you use N-310 2.5grs . If you search my past posts you'll find many 38 special 148 HBWC loads & tests .
3 gr of Bullseye was pretty much standard for me in a 4" Model 10 Smith&Wesson .38 Special. Works good with 158`s too in lead. It`s slow but accurate. Sorry, I never tried the powder you have.
Good shooting
Jim