Just my opinion here but I would never run loads with H110/W296 in anything but an 'N' frame. Yes, the 686 is indeed a .357 MAGNUM caliber but sometimes just because you can doesn't mean you should. It will be hard on the gun, massive flame cutting on the top strap, multiple fireballs on every trigger squeeze will be daylight bright HUGE, loosening the cylinder in the frame, etc. depending on how much you shoot.

I remember all the different things I tried to get an honest 1150 fps from a 125 gr XTP in a 1-7/8" barrel J-frame. H110 never even got close to that velocity and was super unpleasant to shoot. The load that actually got the stated velocity was actually not that bad to shoot. All the initial shots were fired through an Oehler 35P from a 6" N-frame model 28 before they went through my 340PD.

I accomplished my goal but long story short, it cost me my 340PD. It was a fun experiment and I learned a lot along the way but the cost was a bit high. Could I talk my way into S&W replacing my gun? Maybe but it wouldn't be even remotely close to morally decent.

FWIW, I have put together and shot many thousands of .357 Magnum loads with HS-6 powder that are fast, accurate, give a good magnum 'feel' to the gun, and are fun to shoot.

YMMV, just my $0.02