Hey A300-
Well just to let you know I did a few flight with 3 c/a's on the A320 and have also done flights on the A300-600 with 7/6 cabin crew on it. Was it legal dont know because everyone baffled us with the answers
A320 - at qatar can operate with 3 crew as far as i am aware due to pax numbers 132y 12f/c total 144 so ok as far as 50 pax per crew L1 door cabin senior 4L/R two cabin crew
A300 doors 3 L/R were classed as secondary exits/pax self help ones and were told no need for cabin crew as were short and you can go.
So for anyone to say it hasn't happened sorry it has
Hope this can clarify things a bit for some people.
Happy Flying