Use the search function to find various discussions of spigots and fit. One of them might apply best to what you observe in greater detail. Note that spigot ferruled rods don't "seat" to the point that the blank ends touch one another. Here's one: viewtopic.php?f=32&t=49802&p=226334&hilit=conical+mating+surfaces#p226334
That rod has been retrofit as jgestar pointed out, and with a makeshift spigot much longer than necessary with a sound blank
. Short sleeves, much bulkier than necessary with a sound blank
were installed to reinforce the blank ends against splitting.
Look for more detail than can be seen for sure in the very helpful pics. I think that is not just a retrofit for the sake of installing a spigot. Instead, I think it was to utilize mismatched sections, or to compensate for a damaged original tip section. That's because the outside diameter (OD) of the tip section appears to be smaller than the OD of the spigoted end of the butt section. Tubular glass blanks designed for metal, spigot, or sleeve ferrules are produced as one blank and then cut at the ferrule position. Thus, if you can visually align the blank at that cut point, the ODs will match or show continuity with the mild taper of the blank.
On that rod, it looks like an inch or two of the mid section where the ferrule once was is missing. Perhaps it was broken there or damaged in a previous repair of the metal ferrule. The repair was to cut out the damaged area and install a solid glass spigot that was never intended to be fully inserted in the tip. An inch or two was to be exposed, keeping the rod full length by replacing the damage end(s) of the rod section(s). Or a mismatched tip section was used to compensate in the same way.
That's all assuming I am eyeballing the diameters close enough. You can tell for sure by viewing them together or by measuring. My guess is that if you measure thelength of the blank section of the tip and the length of the blank section (not the spigot) of the butt, you will find the tip is about 2 inches short, this length lost from its lower end.
My eyes could be crooked and I could be wrong, but you can tell for sure by measuring.
One further guess, based on abrasions on the butt section. The rod was used--after the repair, at least--for trolling or casual bait fishing as many fly rods were, not for much fly casting. Look at the guides carefully for signs of grooving.