Because this is the forum for a 22 caliber rifle, and because no one else has mentioned the elephant in the room, I will.

People say the 40 S&W is "snappy" and harsh shooting, compared to the 357 Magnum it's a Powder Puff. Seriously, 3 or 4 cylinders of range ammo and you'll understand why probably 95% of 357 Magnum owners shoot the much milder 38 spl. in these revolvers 95% of the time. That stiff recoil means that recovery time will be extended and accuracy will also likely suffer due to poor recoil management.

Another issue is that the 357 Magnum has a distinctly LOUD report and this is one reason why I think it's a poor choice for a Defense caliber. Shoot a 357 Magnum indoors without any hearing protection and it's a near certainty that you WILL lose some of your hearing. How much depends on how big the room is and how much soft furnature is in that room. Fire a 357 Magnum in a hallway and you'll probably lose all of your hearing. Yeah, they are that LOUD.

Now for a bit of good news. That is that any 357 Magnum can also be used with 38 spl., 38 +P, or 38/44 loadings. All of which work well for defense provided you shoot straight. As for the differences, in terms of Muzzle Energy the 38 spl. runs around 200 ft.lbs, the 38 +P around 250 ft.lbs. and the 38/44 can get up to 350-450 ft.lbs. BTW, the 38/44 is basically a custom loading that led to the development of the 357 Magnum and today only Buffalo Bore markets a load I would classify as a 38/44 loading, see the following link.

Heavy .38 Special +P Pistol & Handgun Ammunition

Revolvers. First, for a first 357 Magnum I recomend going with a revolver that has some mass. At near 700 ft.lbs. of muzzle energy for some loads starting out with a 340PD that weighs under 12 ounces is IMO just plain STUPID. I would recomend the S&W 686, Ruger GP-100, or S&W model 627, all in a 4 inch barrel length. If yourbudget is tight, the 686 will be both the easiest and likely most economical to find, it's been produced in very large numbers and good used samples are easy to find. Prices for a used 4 inch 686 should run between 375 and 525 dollars, depending on condition. You can also sometimes find used Rugers in 357 Magnum at slightly lower prices but it's a matter of luck in finding them.

Because there are specific issues in terms of function with revolvers I would suggest that you find a real revolver specialist to go with you whenever considering the purchase of a used revolver. At the least you'll want to do a google search on "how to check a revolver" and do some reading. However, some of these net postings are INCORRECT in some aspects of checking timing so don't assume any net article is truely correct.