The diameter is the least of your issues. Anything from .355 to .357 should be ok, if not necessarily ideal. Your gun will have it's own preference.
IMHO, you very likely have a powder measurement problem. Itty bitty powder charges can be a PITA to get consistant in a lot of measures.
FWIW, I reload cast 95 & 100 gr bullets in .380.
“At the core of liberalism is the spoiled child – miserable, as all spoiled children are, unsatisfied, demanding, ill-disciplined, despotic and useless. Liberalism is a philosophy of sniveling brats.” — P.J. O’Rourke