Yes.. offhand, I know of two. Magnum Research made the Desert Eagle available in .357 Magnum, and Coonan Arms manufactured a semi-auto .357 Magnum, based on the M1911 pattern pistols.
The first production semi auto pistol was the Mauser c/96 "broomhandle" pistol.
Kel-Tec manufactures a Model PMR-30 Semi-Auto pistol chambered for a .22 Magnum cartridge (.22WMR) with a 30 round clip capacity.
The S&W .500 magnum is a revolver cartridge, and not suited for a semi-auto pistol. The DE is available in .50 AE, not .500 Magnum
Yes
In order to tell how old your Colt 25 semi auto pistol is, you will need to offer the serial number. This number gives you an idea of when the pistol was manufactured.
Yes, there have been a couple. At least one company (Coonan) has built a semi auto pistol that fires the .357 Magnum cartridge. A much more common find would be handguns built in the .357 Sig caliber. This is a bottlenecked .357 cartridge intended to duplicate the performance of the .357 magnum, but in an auto pistol cartridge.
There are a very few semi-auto pistols that shoot .357 magnum (not .357 Sig). While they will fire .38 Special, it is as a single shot- they will not cycle the action.
Semi-auto requires the hammer to be cocked for the first shot.
15m
@1893
15m