Originally Posted by PistolRogue
Bill, even at 50 shots (which my gut tells me has to be a bit optimistic), I really have to strongly advocate for a changer knob like the SR1. You'll have to drill and thread for some kind of plunger to pierce the 12g anyway, just like the 3357 has the screw in the bottom, so why not make it so the 12g easily drops out of the grip like it does on a Duck?
For the valve size, I don't see 50 being overly optimistic, but the SSR/SR1 knob has been my argument based on the same reasoning as yours. Not all 12ies are the same size, might as well make it a convenience since you're going to be milling anyway.