This is probably the 2nd most commonly encountered bullet mold - a .40 calibre No. 1 Conical and No. 2 Cylindrical bullet cavity mold. Dimensions are different for the 1873 bullet and the 1882 bullet and they should not be shot in each others barrels. I don't believe you can tell the difference simply by looking at them - if someone knows how to differentiate between the 1882 and 1873 bullet molds - I wish you would let us know.