Pupfish, if I grind the bottom flange of the rail the lens just fits inside without the cap on but I think I just work around it even its a PITA to travel with.

2F, yeah I figured that out when I checked the price of Graphics lens board. Luckily, the Sironar came with a graphics lens board.
This lens has Copal #1 and others are #0 so it's good to have its own.