wpsdlrg, no worries. That's exactly what I'm talking about. I had wondered if this had ever been done, either as an original design or a careful modification by a responsible smith with precision techniques. I'm not going to try cob-jobbing this in the basement with JB weld or anything.
Pahoo, wasn't that presented in the original post? Relative to the numbered points in the original post, the goal would be to (1) increase efficiency in sending more pressure down the barrel and (2) prevent the flame blast orthogonal to the barrel at the cylinder.
James K, it would have to be specially designed. For instance, the frame could wrap around one side of the cylinder. A door completing a cylindrical enclosure for the cylinder could be mounted to the crane. It could swing open, extract, and load normally. When closed, this door would seal against the frame and enclose the cylinder, forcing cone, etc... It wouldn't have to be that much bigger and would probably be most helpful in the case of those rifles which employ a revolver mechanism.