Isn't a 686 a .357 Magnum gun?

This thing won't even sneeze with this load. You're at 17kpsi and the gun is made for 35kspi along with the brass. Believe it or not most 38 special brass have the same dimensions as .357 mag brass other than the length. Your cylinder is holding the pressure in on the sides and your breechface is holding the rim. If the gun can take it, the brass will take it.

You should be getting around 800 fps out of the gun which will be easy shooting. At 800 fps, the lead bullet can also take it.