It's VERY hard to ever wear one out, even with heavy use in practice using standard ammo.
BTW, lets say you DID wear one out after only 50,000 rounds or so. Assuming you pay $15 per box of 50 rounds: $15 x 1,000 boxes of 50 = $15,000 worth of ammo.
ALWAYS, the handgun is the CHEAP part of this sport, and if I ever wear out any of my S&W revolvers, I'll just replace it. So far, at age 61, I haven't done this even once yet, although I shot competitions for years, putting tens of thousands of rounds through some of them in practice.
Just avoid the 125gn. stuff and, if you want to see maximum life as a competition shooter who shoots hundreds of rounds per week into a revolver, do what virtually all competitors do . . . invest into reloading equipment to save tons of ammo money . . . and also "download" your hand-loaded ammo to lower velocities vs. combat/self-defense velocities. It is easier on the gun . . . and easier on the shooter too!!!
Enjoy your 686 and shoot the snot out of it. They'll almost certainly still be running long after someone inherits it from you!