As I understand it MG4 RC prints as grade 2 without a filter, as does most MC paper, but I personally would always use a filter to obtain the correct grade as in my experience with MG type papers you do not get a ''true'' grade with out the correct filters, if you compare an unfiltered print and one with the 2 filter you can see a marked difference, besides which, why would Ilford include a G2 filter if it was not needed, besides which I understand the OP problems started when he was trying to make a print without any MG filters, and could not get a decent print,