Thank you gentlemen. All of the Roper shells I have heard of were steel. That said, I think there were rifle shells, too. I'll attach some pictures, but I don't have one to measure. They came in at least 16 and 12 gauges. The picture with the orangish background seems to show multiple gauges,or maybe rifle shells, some of which are a bit unlike the first one I'll post.
Here seems to be a variety of Roper shells. I do not know where I got the picture.
Here is a gun and shells for sale a while back. As I recall it was a 16 gauge.
Here's the Roper patent #53881 of Aprl 10, 1866