Brownells Pure Tin Bullet Casting Metal. Tin pieces are roughly 1/2" long, 1/2" diameter. There is about 1 pound of tin per bag. Tin melts easily and is great for making custom casting alloys or mixing with other alloys to increase hardness. As a basic rule, for every 1% of tin added to lead, you can expect a Brinell hardness of 0.3. Sold by the bag, weights are approximate.