The metal bbs cant be denser if they are the same size and weight. To make somthing denser you have to put more mass in a smaller area. So a lead bb of the same size as a titanium bb the lead bb will weighs more because that lead is a denser metal and also weighs more. The greater the density the greater the weight. This is true unless an object is created larger. If you had a bb made of lead that weighs the same as a titanium bb but the lead bb is much larger than the titanium is more dense if the same amount of metal is used for making each bb.
