I think the 24 gauge that ellenbr is thinking of is an H&R. I saw one years ago, but it wasn't a true shotgun. It was some kind of an animal dart gun if memory serves. They had one at an auction I went to, it was a smoothbore but had sights on it.

I have an American made 24 gauge shell in my collection, it's a Winchester if memory serves. I believe it's the only one I ever had a chance to buy.

Destry

Out there at the crossroads molding the devil's bullets. - Tom Waits