The uneven gap is not a good thing, but probably not the cause of spitting. More likely the cylinder is out of alignment to the barrel when the round goes off, shaving some bullet material. The forcing cone may need to be a bit larger too.

All this is fixable. Set the endshake, set back the barrel, recut the forcing cone, retime the cylinder. These are all commonplace things for a good revolver smith. Probably a good idea not to shoot this gun until these issues are addressed.