The Scout can be seen wielding this weapon in Trailer 2 and the Illustrative Rendering in Team Fortress 2, showing it was still in the relatively late development state of the game. However, the weapon was scrapped before the final release for unknown reasons. The Scout was equipped with the Scattergun as a replacement.
Information can be found in
"TF_Weapon_Nailgun" "Nail Gun"
- The Dispenser, regardless of level, has what appears to be a nail belt in it.
- A bucket icon for the Nail Gun can be found in the game files.