Haven't tried on a Jr. Statesman, but since the size of the tip area is pretty much the same as the Jr. Gent, I can tell you my experiences with that. Mont Blanc will fit, but it is a tight fit, and the tip doesn't quite stick out as far as some might like. Some have suggested filing the inside of the opening using a nail around which sandpaper has been wrapped, but I haven't gotten that brave, and on my personal pen simply deal with the fact that the tip doesn't stick out as far as with other refills.