If the snub is not designed for +P and you use +P the stopping power and penetration don't mean squat when it blows up in your hand. I have a Model 36 Smith and the manual specifically states "DO NOT USE +P AMMUNiTION"!
You have to know if your revolver can handle the pressures of +P. I have personally witnessed 3 events of revolvers coming apart from +P ammo. They were not pleasant experiences.
If you have time to do it twice, then you have time to do it once right and put your name on it