eBay had this very interesting mould listed:
The numbers are in the same location as on other Harvey moulds (see here) so there is a sense that this isnt something that someone stamped in their workshop. The interesting part is that there are no Harvey bullets listed below .35 caliber. Harvey offered his Prot-X bore moulds through Lakeville Arms, rather than Lyman, so it is possible that this was simply a design that was strictly available only through Lakeville and not Lyman…therefore Lyman wouldnt have much about it in their books. The #521 is the correct range of cherry numbers for this sort of thing, the 500-series having been set aside for special projects and custom stuff like this. However, examining the moulds cavities introduces more mystery.
The bullets are smooth sided, which is typical in some Harvey designs, but there is a distinct lack of a groove to seat the washer in the mould. Most moulds, when drilled out by amateurs, usually have the ‘nose’ of the resulting slug looking very much like a drill bit. Not the case here. .The cavities look very good and dont give the impresion that the mould was modified. I suppose it is possible someone who got tired of messing with the washers could have milled out the groove for seating the washer, but the mould looks awfully pristine for that. Perhaps this was simply a core-type mould and the zinc washer was swaged on later?
Further research shows that in addition to the Prot-X bullets, Harvey also had Lyman make up moulds for casting cores to be used in half-jacketed wadcutters. These moulds were #357511, #357512, #429510, #429513, and possibly a few others. These moulds were also marked with PROT-X and Lakeville Arms. Most likely, Harvey simply had the one stamp for the mould blocks. The cherry number of 521 is in the range of the custom/special orders and it most likely a .30 caliber RN core for someone to swage a jacketed RN bullet. There is no groove in the mould because this bullet wasnt designed for the washers, it was designed to go into a jacket and be swaged.
The mould is a nice piece of obscure history. No mention of it appears in any of the Lyman or Ideal catalogs or handbooks. This isnt surprising since the moulds were supposed to be available exclusively through Harvey (special moulds made by Lyman but only available from another source is something that Lyman has done a time or two…most notable with Harvey, Freedom Arms and Wildey.)