I have a standard action stripped on the desk in front of me. As it stands it is approx .060 short in the action well. However IMHO the removal of that .060 would not make any significant impact on the strength of the action. But looking at it I would if I were building one, I would want to take a little more to ensure reliability of cartridge pick up.
I believe that there were many .404's done on standard actions, but it is not recommended practice today. This may be that there was little reloading done when they were built and more caution is applied today, as the opening up must to some extent, however small that be, weaken the action.