An after thought; I helped my Dad pick out his 1st and only 357 Mag. Of course the wanted a Python but even 20+ years ago they were pricey. I had read all I could on the 586. It seemed to be all a Python was and had the K frame size grip which fit his hand. He hit the bricks and found one in 6". We shot it a lot, I reloaded 357&38's then. It was one fine pistol.
My bro picked it when we drew straws and split Dad's guns. Bro picked it third. He took Grandpas indian axe he plowed up on the Iowa farm as Bro was and is serious into artifacts. I took the pre 64 M-70 Win. I thought he would take the Ruger mini 14 or Grandpas nice Trapdoor 45-70. He took the S&W 586. Good choice for him, it is his constant companion, bedside gun, answer the door late at night fist full and truck gun for his farm. It was his 1st Cf pistol. He like I learned pistols with Dad's Ruger 22 Single Six, had plenty of rifles and shotguns and his own Ruger 22 SS. He like Dad learned CF with the gun. I have tried to trade or buy it, it is not leaving his side.
What does that tell me about the S&W 586/686? It is pretty close to perfection. Unlike the K frame M-19 the L frame 586/686 can handle 357 full time, the L frame has the smaller grip and is comfortable. I've owned 4 or 5 Pythons. I know the arguments for and against, most are internet fables on the Colt, but bottom line is the S&W holds it's own with the Colt, may be an individual gun thing but some 586's will shoot as good or better.
My bro, is not a pistol guy, ask him about old single shot 22 rifles or Rem 700-721's or 870's and he can fill your ears. He also is the chosen one, you know the guy that falls into the outhouse and comes out clean with the prize. One of his employees wanted to sell a S&W 357 he had lucked into cheap so he could buy a deer rifle. Bro bought it sight unseen then called me to get info on his new S&W 357. He said stainless, I asked Model, he had no idea. It was a 4" gun.
I had him put on his reading glasses and open it up, 586, well bro it is nickle, any dash after 586 followed by a number? Nope. Does it have a
"M" stamp, yes. Ok it has been sent back for the factory mod. Dad never sent his in for this.
I did some research and found most of the problem was associated with Federal amo, they had a thinner or softer primer. They changed anmd this was no longer an issue but doubt had been cast on the 586 so S&W did the Mod if you sent it in. We never had any issue with Dad's gun as he was a Winchester ammo guy.
I looked for a 4" 586 until I gave up, I found a few in 6" but moved on. I think many folks who get one hold onto them, Bro also would not sell me his 2 hundred and change 586 Nickle. I ended up buying a 686, new, lock and in 4". Well it is close enough to the cigar to smell the smoke. IT has been great and does lots of night stand with +P 38' HP's and rode in my truck on my farm and at times as a backup in deer season.
When I retired I sold some guns, my last 2 or 3 Pythons went, one in 6" shot like it was laser tuned, but the 686 is better for farm work and for practical shooting off hand one can't tell the difference.
Long after thought. I like my 686, I do not miss the similar size Colt. Both are a 40 cal size frame. If you want to pack it a 4" might do better, if it will be shot more at targets and carried less a 6" is better. Dad carried his in a side holster on a belt and under a towel on the front seat when he traveled. Welcome to the wonderful world of hand gunning and a 686 might be the best place to start.
A disclaimer for the lovers of the N frame guns, I am one and love them. However I find that packing the smaller L frame all day in the woods etc works better for me. And the 5/686 will do anything it's big bro will do. I, at times, think the 5/686 is as close to a perfect 357 revolver as one can get.
P.S. The price seems right, at gun shows all used 6" 586's were tagged more than a new 686 and the folks did not budge. The last ones I saw 5-7 years ago ran 700 plus. I think you will be in love with this one if you get it.