Tin has a lower melting point, 1/3 less density, more cost. The hardness is about BHN 51. You could probably treat it somewhat like a light-for-size jacketed bullet, though you may want to add a card wad or a poly wad to the base to prevent melting with some powders. The lower density will reduce its ballistic coefficient in equal proportion. It also will need a faster twist to garner an equal gyroscopic stability factor, but most handguns already have more spin than is strictly required, so I wouldn't expect to see much from that and it may tumble more readily in game. Because of its lower mass the tin bullet will have proportionally less momentum than its lead counterpart at any particular velocity. If both hold together and don't distort, that would mean proportionally less penetration. However. lead will expand more easily and the light bullet, for the same powder charge, will be going not quite one quarter faster in most instances, so this may not be what you see on the ground.
Bottom line, if you want to try it, go ahead. It should be noted that plants tend to be pretty good filters, and I've not noticed any big stories about problems with lead in crops, despite all the civil war bullets in some places. The EPA's complaints are likely the biggest concern as long as you don't have kids going through the soil and putting oxidized lead objects in their mouths.
