The ironic thing is, I think companies sold the inline idea because it was cheaper to make. Think about it - water pipe reciever and barrel, cap gun breech, and injection molded mattel stock. Other than a central ignition path, I can't think of an advantage. Virtually all I have handled don't have that ergonomic fit of a sidelock. Sometimes efficiency ain't all that counts, but I will concede they function perfectly - so do my sidelocks.