Ok, Ok, youse guys... I know I'm a modern boy with my single triggers. But I do like my double triggers as well. As long as a single trigger is reliable, I have no heartburn with them. A vintage one is a different story altogether.
Like LB said, the BSS single trigger is normally as reliable as a bowling ball.
But, if someone really liked the BSS but for the trigger, the floorplate is cut for double triggers and gutting the single out of there would be no problem. Making some double triggers would be cake, IMO. I have another BSS 20g in a non-selective 28" that I may consider modifying to a DT. Too many projects right now and it IS working. A REALLY good reason to leave it alone ... for now.