Our Catan set has noticeably nonuniform dice. They roll high numbers much more frequently than low numbers; presumably bc the high-numbered sides weigh less (?

Our Catan set has noticeably nonuniform dice. They roll high numbers much more frequently than low numbers; presumably bc the high-numbered sides weigh less (?). We haven't buckled down and done the science but it definitely tilts the game play, to the extent that we're considering swapping them out for new dice. (or this could just be Catan Crankiness (TM), but we've all noticed it quite a bit...)