S&W Model 625
One of the shooters at the Midland Shooters Association pistol competition today used a .45 caliber Smith & Wesson Model 625 revolver (see photo, above). The unique feature of this pistol is that it shoots the same bullet as a .45 caliber semi-automatic pistol. There are some advantages to that. With the full moon clip it can be loaded and unloaded very quickly which makes it ideal for competition. Six bullets just drop into the magazine at the same time, and they pop out just as easily after they have been shot. It's extremely easy.
The Model 625 revolver has an advantage over semi-automatic .45 caliber pistols because the shooter who reloads his/her own bullets can make them with a reduced load to lessen the recoil in order to reduce the time it takes to re-aim for the next shot. So, why can't someone shoot a reduced load bullet in a semi-auto pistol? Well, the semi-auto pistol has to use a bullet powerful enough so that when it's fired it will generate enough pressure to eject the spent cartridge and inject a new bullet into the chamber. And a bullet with a reduced load might not have the strength the pistol needs to allow it to run through the full cycle.
There is a disadvantage, though. The bullets have to be forced into the full moon clip, and it takes strong fingers to do that. But, there are tools that can make the job much easier. And, the same thing applies to removing the spent shells from the clip.
All in all, it's a very impressive handgun.
Update - 1/12/04:The full moon clip for a revolver has a history I learned only yesterday. The Colt 1911 semi-auto pistol using the .45 ACP bullet was adopted as the service pistol, but the factories couldn't produce them fast enough as the country geared up in anticipation of involvement in WWI. So, Smith & Wesson developed the "1917", a revolver that would utilize the same .45 ACP bullet when used with the half moon clip. And, Colt retooled their machinery so that the Colt revolvers could use that same cartridge, too.
But, the half moon clip was inconvenient, and in the 1920s Remington began manufacturing the .45 Auto Rim which had a thick rim which could fill up the same the space that the clip would have occupied.
Both S&W and Colt continued making the 1917 until the end of WWII. Here's a link to an article about the development and evolution of the 1917.
And, at some point S&W began making the Model 625 which uses the full moon clip rather than the half moon clip, and it has become quite popular with recreational handgun shooters because of the remarkable ease and speed of loading.
At a speed shooting and loading demonstration Jerry Miculek with a Model 625 was able to shoot six shots, reload, then shoot six more times with an astonishing elapsed time of 2.99 seconds. Remarkable!