There is no cheap substitute for lead that is near the specific gravity of lead. Tungsten is dense but solid tungsten is not soft. Soft forms of tungsten are composed of tungsten particles and a soft carrier that lowers the overall density. Tin is often used as a substitute for split shot, but tin alloy shot is not near the density of lead. Silver is the closest for both malleability and density.



Here are the specific gravities of some metals in comparison to lead.

Tungsten 19.0
Tantalum 16.6
Lead 11.342
Silver 10.5
Molybdenum 10.2
Bismuth 9.781
Copper 8.89
Nickel 8.85
Monel 8.80
Cobalt 8.71
Iron 7.87
Tin 7.29
Zinc 7.14

Tin is 2/3 the specific gravity of lead. You would need 50% more tin to equal the weight of lead but you would also have a greater volume that would decrease the sink rate even if the weights were identical. In addition, where density per volume is critical as in wrapping lead wire in fly construction, I have not found anything yet that is the equal of cheap lead wire. Silver wire would be the closest but it is not as malleable.

Tungsten is heavier than lead but it is not malleable and must be compounded with a carrier substance that lower's the net specific gravity if it is to be used as a substitute for split shot. I have seen no comparisons of the net specific gravity of tungsten compounds compared to lead.