Les Jones

Only the single-actions based upon the Colt design (Ruger Vaquero, etc) will be easy to reload left-handed.

With automatics, you fare better. Some come with ambidextrous safeties (Beretta 92) or trigger-safeties (Glocks). Others can have ambidextrous safeties installed after market (1911s, CZ-75.
Even if you have an automatic with the safety only for right-handers, you can train yourself to do it left handed by moving your thumb to the other side of the gun and engaging the safety that way.
THe magazine release can be trickier. Practice releasing the magazine button either with your pointing finger, or hitting the magazine release button on another finger joint (this isn't easy, but can be done if you practice and the gun fits your grip). Or you can lower the gun and hit the magazine release button with your right hand.

However, the problem with shooting an automatic pistol left-handed is the cartridges will eject towards the right, and in your face. The only automatic I have found which ejects to the left side is the Walther P-38/P-1, an 8-shot Parabellum, SA/DA.

Shooting a revolver left-handed is fine. Reloading one is another issue entirely. Because the cylinder latch on a DA is on the left side, you are faced with a choice between two very bad evils. There isn't a magic way to do it. You either:
1. Adjust your grip to open the latch with your left thumb. This creates a very weak grip and the possibility of a fumbled or dropped weapon. Crossing hands to load with a speedloader is also a problem.
2. Transfer the revolver to your right hand and open the latch with your left. Changing hands under stress also increases the possibility of a fumbled or dropped weapon.

As a lefty, I consider any revolver to be non-reloadable under stress. If you're empty, just put it down and dig for your backup. That's the only reliable plan.

Gun manufacturers especially those who make revolvers are missing the opportunity to make lots of money by limiting their products to right handed persons.
Hope that a gun manufacturer like Wesson Firearms produce a new revolver for lefties with different specs i.e. in medium frame, 7-shooter, 5-inch barrel, stainless, with competition trigger - in magnum .357/38 +p+ spcl and magnum 41. Think of the more than a million lefty shooters around the world who fancy revolvers.

Calling other gun manufacturers who cater to lefties like us.

Shooting and reloading a revolver is not a big deal for us lefties.... as long as you take time to practice a little. The trick to reloading a Smith and Wesson (I've not used a Colt) is to use your trigger finger to push the latch, and to reload with your right hand. Crossing hands over isn't nearly as awkward as some folks seem to think.... after a few reloads it comes natural, and is just as fast as a rightie can do.

I'm right handed, but shoot left handed due to the eye dominance thing. A fast reload is not a problem with a little practice. I use my trigger finger{ I ain't got no bullets left anyway}, hit the latch, and with my right thumb, grab the cylinder { kinda' opposite of a traditional right hand reload grip}. It seems to work pretty good, especially if you shoot a ruger.

Charter Arms makes a revolver for lefties, called the Southpaw, in 38 +P. That is the only one I've been able to find. I think if Charter came up with a couple more models (maybe a four or five inch, .357) they wouldn't be able to keep the shelves stocked!