What is a Rebated pistol cylinder?

Answer 1

It is where part of the cylinder is cut in, allowing a part on the frame to match up. Use a search engine for Rebated Cylinder, and you'll get plenty of pictures. "Cut in" means that the diameter of the cylinder is reduced at some part normally by "cutting in" with a lathe. In some black powder pistols, especially early colt models, the diameter of the cylinder is less at the nipple end than it is at the end closest to the breach of the barrel.