My advice would be to check out wikipedia and the manufacturer's website for the gun you pick. Details count.
A recent book I read mentioned a character having a German Glock Revolver. Glock doesn't make revolvers, and they're based in Austria. Double whammy!
One thing that I've noticed is that some people confuse "revolver" with "automatic", or think they're synonymous. So, here's the Reader's digest version of the differences:
Revolvers use a rotating cylinder with spaces for each shell+bullet (aka "round"). Think "old west" gunslinger type movies. These guns were king of the handgun realm in the mid-late 1800's. Pulling the trigger (in a double-action revolver) causes the hammer to come back, the cylinder to rotate so a bullet is in position, and the hammer to come down on the back of the shell - hitting the primer cap to ignite the gunpowder, shooting the bullet out. If the chamber is empty, you get a "click" and no shooting.
With (most) semi-automatic pistols (aka "automatics"), the gun loads by placing a magazine (loaded with bullets) in the chamber within the handle until it latches in, and sliding the slide (top of the gun) towards the rear. This also pulls the internal hammer back, ready to strike a firing pin. Once the first bullet is chambered in the barrel, it's ready to fire. If you never slide the slide, it's not loaded. Most people who don't want to accidentally shoot themselves will either 1) not chamber the first bullet, or 2) use the safety switch if a round (shell+bullet) is chambered. Firing the gun is done by pulling the trigger, which releases the hammer against the firing pin, which hits the primer cap, which ignites the powder, shooting the bullet. The recoil from the explosion is used to move the slide back against a recoil spring (or springs). The empty shell catches on a hook and gets tossed out, the hammer gets pulled back again, and the slide moves forward to chamber the next round.
It's fun to watch in slow motion
Automatics started appearing in the late 1800's. The Colt 1911 .45 caliber pistol has had a long and glorious career in the U.S. Military since that time (from 1911 to 1985). It was replaced by the Baretta 92F (9mm).
If a guy is going to kill himself with a gun, he wouldn't wuss out and use a .380 because it might not do the job. A .45 would be a good choice. Baretta's model 92 9mm semi-auto may be popular, but the firepower doesn't match the Colt .45.
http://en.wikipedia.org/wiki/Semi-automatic_pistol
http://en.wikipedia.org/wiki/Revolver