I use that same load of Lil Gun under 158 gr JHP'S and LSWC's with CCI Magnum primers in my .357's. Good load. JHP = 1270 fps , LSWC = 1341 out of a 4" 66. No signs of pressure, but certainly hot enough to keep me from seeking the 18.0 gr max. I think Lil Gun needs magnum primers.