A 586 is a good gun, just like the 686 only in carbon blued steel rather than stainless. Some prefer the look of blued whereas I always prefer stainless as I think it is superior, at least in anywhere near modern stainless guns-with the exception of copies of historical guns. The no-dash means there is no dash after the model designation. A dash followed by a number will indicate later runs of guns with changes to them-sometimes inconsequential, other times of significance. IIRC the early L frames had some bugs to work out, but I can't remember what they were. Many of these no dash guns were sent back and fixed. Smith usually designates that also by stamping the gun.
The N frames are stronger than K or L frames by way of mass. They are simply bigger guns and thus stronger. The N frame predates the K frame in 357 Magnum. Bill Jordan called for a K frame in 357 and is thought to be the father of the model 19-which is strange since Jordan was huge. It was thought that the time was right for a smaller 357 since by then the steel was better than a turn-of-the-century Hand Ejector say, which turned into the model 10. By the time the L frame came out, the N's were thought to be overkill for the 357, hence the emphasis nowadays on putting more holes in the cylinder of new iterations of 27's and L frames.
The L frame was brought out specifically to compete with the Python, which is one reason they have the underlug, mimicking the Colt gun. They are said to be a .41 caliber frame, which is enough mass for the hot 357 cartridge. For many years Smith bracketed the Python, et al with a .44 caiber N frame and a .38 caliber K frame. Now Smith even makes tiny J frame 357's. Colt beat them to that with the Detective Special.
