I remove mine from the action when I put it in the hard case as it sits a bit proud otherwise.
At present, to stop it rattling about, I put it in a cut off tube of rubber I have left from a T8 moderator tube but I am always concious of squeezing the rails together and make sure I don't.
If a leather case was made for it, it would have to have some sort of divider to make sure the rails stayed apart and not bent.
If anybody came up with a good idea and at reasonable price, I'd be interested in one.