Ejectors on most guns are cocked by the closing of the gun by being pushed in by the breech face. They thus assist in opening only if the gun has not been fired. When the gun is not fired no assistance is needed, the weight of the barrels is normally sufficient to open them as the hammers are stil cocked. A few guns are different of course but this sums up the vast majority of hammerless doubles.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra