This ^^^A leg off an old pair of jeans, cut to length, can be hand sewed shut after filling with your choice of weight, even old wheel weights work well, pea gravel ect. works well too...
DM
Maybe I'm a wimp, but that seems like an incredibly bad idea to me and I've probably dropped a couple thouand pounds worth of freshly cast bullets into icewater to heat treat them.You can pour molten lead in a bucket of h2o and make your own shot,just melt some WW's on a camp stove/fire in an old cook pot and pour then put it in a bag.Don't forget your safety gear!!!