I don't put as much stock in outdoor hand timed 40s as I do in indoor electronic. Reason being besides the obvious human inaccuracies, however great or slight they may be (can be several hundrenths to a half second off here, outdoor you also have headwind/tailwinds, which can also make a difference in either direction.

When I hear of someone's 40 time, the 1st 2 questions I ask are:
-Was in indoor or outdoor?
-Was it handheld or electronic timed?

If I hear outdoor handheld, I take it with a grain of salt.