Question: what is the difference between a 12 gauge shotgun?
Answer: In short, the smaller the gauge of a shotgun, the larger the bore diameter. ... So, 12 round lead balls of 12 gauge diameter would weigh 1 pound, but since they're smaller, it would take 20 balls of 20 gauge diameter to weigh a pound. There is one exception to this rule: the . 410 bore.