7x57Hunter,
Your No.457474 was listed only in Handbook No.39 (1953), with only the briefest of mention in the first Handbook of Cast Bullets (1958). Apparently, this was intended as a "double cast" design (note the 'dotted line' indication in the illustrations below). The nose, with a tapered tail piece, would be cast in a separate mould, of presumably a soft alloy. This nose casting would then be placed into a "full cavity" mould (as the one you have) and a harder alloy poured to make the casting complete. This, in theory, allowed the caster to "make your own soft-point". It was pointed out in a later handbook that this must have resulted in a very high rejection rate... placing a cooled nose casting into a mould, then attempting to pour the base section in behind it. Yikes!!
Anyway, below are images of the relevant info for No.457474 and the .45-70 cartridge from HB 39 and 1st HCB. Oddly, HB39 doesn't give loads for specific bullet numbers, but only for general bullet weights.
Handbook No.39:
Attachment 319873
Attachment 319874
Attachment 319875
Handbook of Cast Bullets:
Attachment 319876
Hope this helps you,
Jim