jos wrote in another thread:

Quote Originally Posted by jos View Post
...The caps of the M400 are however readily interchangeable with the caps of the M600 "Old Style" (1985-97)....
I've owned many Pelikans over the years, but to keep nib swapping simple, I never aspired to owning Pelikans larger than the standard M4xx/M2xx/M7xx/M101N pens. I have always assumed that M600 pens were larger than the M400 and smaller than the M800, and I recall Richard Binder's Pelikan nib webpage noting that the M600 nibs will fit the M400's barrel but are still too large. Then I read jos's comment (above). If the old style M600 cap fits the M400 barrel, wouldn't the old style M600 threaded barrel therefore be the same diameter as the M400? So just what are the differences between the M600 and M400? Length? Nib size? Quality of materials (vis-à-vis M4xx and M2xx)?