Lead encased in copper.

[Dennis]

Some members have also recommended West 1 Castings, Hatton garden. You cold also consider having them cast in two halves and soldering together, to save weight.

My pictures show an experiment for suspending a bullet horizontally:
1. A bamboo bullet, a large soldered jump ring, a burr shank.
Insert the bullet, twist first with pliers and then using the burr shank.
2. Cold connected suspension. You might need to make shallow grooves on opposite sides of the bullet. Dennis