The best way to measure trigger pull weight for a revolver cocked into SA (or a cocked 1911) is to use weights, and know how to use them. This means being taught how to observe the cocked trigger "hold" at a weight, and then having the trigger tripped to fall with a slight movement of the gun.
Back in my S&W revolver armorer class notes, and in an older S&W revolver manual I inherited from the former head armorer, the
minimum trigger pull weight for a S&W revolver cocked into single action is 3lbs. Minimum. That doesn't mean it can't be heavier in any particular revolver, depending on the tolerances and how the parts fit.
Now, the perception of people can easily vary. One person's "hair trigger" is another person's "could be lighter and still be within normal spec" trigger. Also, some people haven't been trained to regulate and control the force exerted by their index fingers, and they have a hard time realizing how much force they may be exerting, and how quickly.
If you're curious or concerned about it, probably the best way to know the condition and SA trigger pull weight of
your 686 is to have a gunsmith check it using traditional weights. if it's a new gun, the factory could also check it under their warranty. Most people complain about how they feel new production revolvers have too heavy of a SA trigger pull, though, not too light. Might cause a factory revolver repair tech a moment's double take and chuckle. (Unless it IS too light to be within spec, or has a 'push off' problem, and then they'll correct it.)
Congrats on the 686. A great (but heavy) stainless revolver. I carried a couple issued ones back in the mid/late 80's. Should've bought the last one when they offered us the opportunity to buy one ($235, I think was the price offered to us) when we transitioned to hi-cap 9's. I think I only had just over 3,500 rounds fired through the second one, and it was fine revolver for a working gun.
Also, try not to have your finger on the trigger of the cocked revolver is you feel a sneeze coming on ...