OzFclass

Plaster of Paris is the same. It takes forever to lose moisture unless you can stick it in an oven at low temperature. Been there, done that.

My wife said that plaster of paris has less shrinkage..... the oven would be fine, i have oven privileges ...

oh well i may not need to try again for a while... if anyone does make sure you wear eye protection !

I have made additional weight for a stock by mixing lead shot with silicone. Works well but messy if you aren't careful. Absorbs vibration nicely too.

Lead shot mixed with polyester casting resin (or normal polyester resin but be careful not to use too much catalyst or it can catch fire) in a mold works also.