I tried the soft point method of dropping a few pellet gun pellets in the cavity, setting the mold in the melt till pellets melt, let briefly solidify on flat surface, pour in harder alloy, let briefly solidify on flat surface, set mold in melt to remelt and fuse the two columns. I get a nice seamless and square transition this way but the pellets leave a somewhat thick oxidized layer as a barrier between the two layers bonding and some failed and that point in hydraulic press test and the front pops off.
any tips?