Bought my 36 when I was in the police academy in 1969 No +p ammo then and super vel was just coming out. One of the cops was into reloading reverse hollow base wadcutters backwards and he loaded them hot. I mean very hot, probably more than any +p factory load today. We took them to the range and tried them on different objects including a sheet of what was then considered "bulletproof glass" like they used for bank windows. Can't remember if they went through but they shattered and spiderwebbed it with no harm to the model 36.
I still have mine and it's as tight and accurate as the first time I shot it. S&W will tell you not to use +p but I think that's for liability (CYA).
Those older Smiths were tough and maybe even tougher than the aluminum and whatever stuff they make today that's rated for +p.
Not saying I'm right and know it all but it's worked fine for me.