Tap a oversize .360" bullet into the barrels throat. Measure. Size to .0005" smaller.The mold drops right at .356 and I powder coated them and sized them to .3560"
Looks like a different mold is needed that will produce a LARGER as cast diameter. Pure linotype can add as much as .002" to as cast diameters.
Fit is KING. (after adding some linotype.)