The swing-out cylinder DA/SA revolver has been around since the 1870s and has been refined in many ways. While there are variations in the common brands and models, they pretty much remain alike with their handling. However, they usually differ in the way you get the cylinder open for extraction and loading. Colt always used a pull-back latch, originally “L” shaped and evolved into a gracefully rounded knob. Smith & Wesson favored a dished-out button that you pressed forward to allow the cylinder to swing out. When Dan Wesson came along with the flat lever that tilts down to release the cylinder, it was mounted forward of the cylinder on the left side of the frame. That unusual arrangement drew criticism until PPC shooters discovered the utility of the system’s ease of reloading.
Taurus became a force in the market in the 80s and stuck with a system similar to the S&W in that the dished out latch went forward. Interestingly, when Taurus started making big magnum revolvers, they went to a system that required a Dan Wesson-type latch along with a S&W type latch—two latches. Ruger’s first DA/SA revolvers were introduced in the 1970s and proved to be fine sixguns. The cylinder latch was, in my opinion, the best of them all. Mounted high on the left recoil shield, a lever is in direct line with the cylinder axis, completely out of the way of speed loaders. The latch tilts inward.