Just to cover another reason why there are no modern breaktops. The extraction system used with most breaktops has a short throw cam, meaning the extractor will not work with long cartridges. The S&W Schofield worked OK with the short .45 Government round, but would not have worked with the .45 Colt even if the cylinder had been lengthened. The extractor of the Webley Mk IV works fine with .38 S&W; it would not work with .38 Special or .357 Magnum. A manual extractor would work, but one of the main advantages of the break top would be sacrificed.