While looking through Gunsamerica and a few other sites that offer shotguns for sale. I notice quite a few 16ga guns. Some pretty old but some that are new in the box(saw a few nib 870s). I have only shot 12 and 20s and I thought that 16s were a dead issue and there doesn't seem to be a lot of ammo available. Please excuse my ignorance. Does the 16 GA have any advantages or has it fallen into the background cause the 12 and 20s?