Few random questions

Is there a better replacement suggestion for the washer combo's that the Diana 54 AirKing uses?

On a Beeman RX2's there is a very small trigger guard screw that goes on top and to the side of the front trigger guard screw. I think its the front one. Maybe some type of lock or security screw to keep the larger screw underneath it? Anyway does anyone know what size it is?

Lastly, when is a breach seal considered "too proud" when its in the breach block?