The Vulcan BF-50 is a Nerf blaster and the prototype of the Vulcan EBF-25. It went through a lot of changes in its design before it became the finalized blaster. It is now used solely for special Nerf events and cannot be purchased.
The Vulcan prototype has a semi-automatic firing mechanism, unlike the fully automatic system of the final version. It is roughly double the size of the production model, including the accessories. The ammunition and belt are also large in size to match the blaster's priming mechanism. It also has a belt catcher on it, unlike its successor, which uses a box to contain the emptied belt links.
This blaster shows us that the electronic belt fed series was originally known simply as "belt fed".
The fifty-dart belt seen with this blaster has not made an appearance since.