John,
Don't know for the Baron but the nib's Churchill is removable and interchangeable.
The peculiarity of the Churchill/El grande is that their section IS their housing. That is, feeder and nib are just pulling out the section/housing.
Okay, from what you say, I will try again. The last time I was afraid to break the feed fins. I need to be able to offer different nibs on the baron without buying the whole housing.