I'm a mechanical engineer and think about the design of mechanical devices all the time. I guess it's one of the reasons I like guns, as well as hand-wound wrist watches.

I was thinking about the design of most auto-loading pistols. There is a common design concept that uses a moving slide external to the barrel and a barrel that is floating, which tilts as the slide moves back. One of the exceptions to this concept is the Ruger Mark series pistols. They use a barrel fixed to the grip frame and a moving bolt within the barrel and receiver.

To me, the Ruger design is quite elegant. The bolt is positively guided, the sights don't move with respect to the barrel and the bolt is much lighter and easier to cycle than a slide.

So now I'm wondering why other pistols aren't designed like the Ruger. Patents? Cost? Is there some mechanical reason why larger-caliber pistols can't use this design; grip angle, bullet geometry for loading, etc.? Are there any centerfire pistols that run like a Ruger?

--Phil