Do not let the hammer rest on the primer in any gun that has an exposed hammer. Problem is that something can catch the hammer and detonate the primer. Some revolvers have a half-cock or a rebounding hammer, but you should never trust any safety device to work perfectly all the time. Better safe than sorry. You can rest the hammer between cartridges on a Schofield, but that is still not a 100% guarentee of safety.
Bullets in the leg or foot can be quite painful! CAS only allows 5 cartridges in a six-shooter during shoots and the shooter must carry a loaded gun with the hammer on the empty cylinder.